FORM-2 THE PATENTS ACT, 1970 (39 of 1970) & THE PATENTS RULES, 2003 COMPLETE SPECIFICATION (See section 10 and rule 13) PROCESS AND COMPOSITION OF A NEW CATALYST/ADDITIVE FOR REDUCING FUEL GAS YIELD IN FLUID CATALYTIC CRACKING (FCC) PROCESS RELIANCE INDUSTRIES LIMITED an Indian Organization of 3rd Floor, Maker Chamber-I, 222, Nariman Point, Mumbai-400021 Maharashatra, INDIA Inventors KUMAR Dinda srikanta, Chinthala Praveen, Gohel Amit, Yadav Ashwani, Mandal Sukumar, Ravichandran Gopal, Das Asit kumar THE FOLLOWING SPECIFICATION PARTICULARY DESCRIBES THE INVENTION AND THE MANNEER IN WHICH IT IS TO BE PERFORMED. FIELD OF THE INVENTION The invention relates to a process for the preparation of a Fluid Catalytic Cracking (FCC) catalyst and an additive for cracking of high boiling petroleum feedstock. BACKGROUND AND PRIOR ART DISCUSSION FCC catalysts and additives have found their prolific use in petrochemical refining industries for improving the profitability of refiners. FCC catalysts are employed to crack low valuable petroleum crude oil comprising high boiling range, higher molecular weight hydrocarbon fractions to more valuable products such as LPG, gasoline and diesel. Since the introduction of zeolite based FCC catalysts in place of conventionally used acid-leached clays and artificial or natural silica-alumina catalysts, petroleum refining industries have observed a remarkable revolution in the designing and formulation of zeolite based FCC catalysts. Designing of the FCC catalysts based on different cracking process conditions and desired particular products have become the mainstay of the refineries. Other than designing the FCC catalyst, use of different cracking catalyst-additives in combination with the FCC catalyst to obtain different products with varying properties and attributes has also been a point of great interest among research communities. For example, pentasil zeolite based additive is used for improving LPG and octane number of gasoline component. SOx additive is used for the reduction of sulfur emission, CO-Promoter additive is used for containment of CO emission while Bottom cracking additives are used for reducing bottoms. In the case of LPG production, the use of cracking catalyst-additive plays an important role in boosting LPG production and/or to improve the octane number of gasoline, however, it also produces additional fuel gases, which may restrict the FCC operation due to reactor cyclone velocity limitation. Further to this, the increased use of cheaper feedstocks i.e. heavy oil/resid/opportunity crudes also contributes towards production of more fuel gas. This is because, in addition to the inferior cracking behavior of heavy feedstock, both metals and basic nitrogen compounds, which are known to poison FCC catalysts, are concentrated in the heavier end of gas oils, especially in the residuum. These poisons, present within large hydrocarbon molecules, deposit on the FCC catalyst, thereby deactivating the FCC catalyst and the additive. This results in production of more fuel gas and coke which ultimately lowers the overall conversion. The higher fuel gas yield often touches reactor cyclone velocity limits which results in lower severity operation of FCC unit, such as lower riser temperature. Similarly, higher coke yield leads to a higher regenerator temperature that lowers unit conversion. Therefore, there is always felt a need to develop a FCC catalyst/additive system, which substantially lowers fuel gas production without affecting the general yield pattern of the cracking products thereby meeting the requirement of LPG, gasoline, diesel while lowering the undesirable bottom or clarified slurry oil (CSO). US Patent 4,451,355 discloses a process for the conversion of hydrocarbon oil feed having a significant concentration of vanadium to light oil products in the presence of a cracking catalyst containing calcium compound such as calcium-titanium, calcium-zirconium, calcium-titanium-zirconium oxides and mixtures thereof. However, the scope of the process disclosed in US4,451,355 is limited to passivate the vanadium deposited on the catalyst during the catalytic cracking process and it is silent on the production of fuel gas. US Patent 5,260,240 discloses a process for passivating the reactivity of nickel and vanadium in a cracking catalyst by adding a calcium-additive with the metal laden catalyst. The process employs an additive prepared from dolomite and sepiolite material for extracting vanadium and nickel from metal laden FCC catalyst in the presence of steam at high temperature. Calcium containing additive found to enhance the activity of cracking catalyst. Escobar et al. (Applied catalysis A; General, vol. 339, (2008) 61-67) teaches the effect of calcium on coke formation over ultra stable Y zeolite catalyst in the absence and presence of nickel and vanadium metal. Different zeolite samples are prepared by impregnating nickel and vanadium on ultra stable Y zeolite, previously exchanged with calcium. The catalyst samples are used for cracking of n-hexane at 500 °C. The study showed that catalyst containing Ca in combination with nickel and vanadium reduces coke formation and increases olefin to paraffin ratio. Komatsu et al. (Applied catalysis A: General, vol. 214, (2001) 103-109) discloses the cracking of n-heptane on calcium exchanged ferrierite zeolite catalysts. Ca2+ exchanged ferrierite catalyst gives higher alkenes selectivity due to less secondary hydride transfer reaction from hydrogen-deficient species. It is also disclosed that the coke formation is suppressed on account of the presence of Ca2+exchanged ferrierite. Letzsch et al. (Oil & Gas journal, Nov-29 1982, 59-68) disclose the effect of alkali/alkaline metal contaminants like sodium, potassium, calcium and magnesium on FCC catalyst. The presence of sodium and potassium decreases the catalyst activity to a larger extent than calcium and magnesium for the cracking of cetane as model compound. The study however is silent on product selectivity with said modifications. The present state of the art is silent on teaching the effect of calcium on product selectivity and its impact on fuel gas yield particularly in the absence of contaminant metals. Therefore, the present invention is directed to the development of FCC catalyst and additive containing alkaline earth metals for cracking of a hydrocarbon feedstock, particularly in the absence of contaminant metals, for lowering the production of fuel gas without altering the cracking products yield. OBJECTS OF THE PRESENT INVENTION It is an object of the present invention to provide a process for the preparation of a FCC catalyst and an additive, and compositions thereof. It is another object of the present invention to provide a FCC catalyst and an additive for the cracking of a hydrocarbon feedstock containing hydrocarbons of higher boiling point and higher molecular weight. It is a still another object of the present invention is to provide a FCC catalyst and an additive for the cracking of a hydrocarbon feedstock that is aimed to boost the production of the cracking products. It is a yet another object of the present invention to provide a FCC catalyst and an additive for the cracking of a hydrocarbon feedstock that reduces the production of a fuel gas without altering the cracking product yield. SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a process for cracking of higher boiling petroleum feedstock to obtain lower dry gas without affecting the yield of LPG, light olefins and gasoline products; said process comprising the steps of: contacting said feedstock under reaction conditions suitable for fluid catalytic cracking with a catalyst comprising (a) a FCC catalyst component ; and (b) an additive component, wherein each of said components independently comprising; a zeolite in an amount varying between 5 to 60 wt %; a clay in an amount varying between 10 to 40 wt %; a binder in an amount varying between 0 to 40 wt %; and an alkaline earth metal in an amount varying between 0.01 to 2.0 wt%, all proportion being with respect to the weight of said components. Typically, the alkaline earth metal in the catalyst is preferably present in an amount in the range of 0.01 to 1.0 wt%. Typically, the alkaline earth metal is at least one selected from the group consisting of calcium, magnesium and strontium. Preferably, the alkaline earth metal is calcium. Typically, the FCC catalyst component comprises a rare earth metal in an amount varying between 0.0 to 2.0 wt %; preferably between 0.6 to 1.0 wt %. Typically, the rare earth metal is at least one selected from the group consisting of lanthanum, cerium, neodymium, samarium, gadolinium, yttrium and combinations thereof. Typically, the zeolite present in the FCC catalyst component is selected from the group consisting of REY, REUSY, USY, beta and combinations thereof. Typically, the FCC catalyst component comprises zeolite in an amount varying between 5 to 40 wt%; preferably between 20 to 35 wt%. Typically, the clay in the FCC catalyst component is present in an amount varying between 20-35 wt%; Typically, the zeolite present in the additive component is a medium pore size zeolite selected from the group consisting of ZSM-5, ZSM-11, ZSM-23 zeolite and combinations thereof. Typically, the additive component comprises zeolite in an amount varying between 20 to 55 wt %: more preferably between 30 to 55 wt %. Typically, the additive component further comprises phosphorous; the amount of phosphorous being in the range of 4 to 16 wt %. Typically, the clay in the additive component is present in an amount varying between 15 to 30 wt % Typically, the binder in the FCC catalyst component comprises an acid treated alumina, colloidal silica and combinations thereof. Typically, the binder in the additive component comprises at least one ingredient selected from the group consisting of phosphorus treated clay, an acid treated alumina and silica. Typically, the binder in the FCC catalyst component is present in an amount varying between 5 to 40 wt%; more preferably between 5 to 30 wt% . Typically, the binder in the additive component is present in an amount varying between 5 to 25 wt %. Typically, the alumina is selected from the group consisting of amorphous gel, aluminum trihydride, psuedoboehmite alumina, gamma alumina and mixtures thereof. Typically, the clay is at least one selected from the group consisting of kaolin and halloysite. Typically, the ratio of the proportion of the FCC catalyst and proportion of the additive component varies between 1.5 to 20 wt%. Typically, the catalyst is adapted to reduce fuel gas production in the range of 20 to 60 % during the catalytic cracking process of a said feedstock. In accordance with the present invention, there is provided a catalyst for Fluid Catalytic Cracking (FCC) process comprising (a) a FCC catalyst component; and (b) an additive component; each of said components independently comprising: i. a zeolite in an amount varying between 5 to 60 wt %; ii. a clay in an amount varying between 10 to 40 wt %; iii. a binder in an amount varying between 0 to 40 wt %; and iv. an alkaline earth metal in an amount varying between 0.01 to 2.0 wt%, all proportion being with respect to the weight of said components. Typically, the alkaline earth metal is preferably present in an amount in the range of 0.01 to 1.0 wt %. Typically, the alkaline earth metal is at least one selected from the group consisting of calcium, magnesium and strontium. Preferably, the alkaline earth metal is calcium. Typically, the FCC catalyst component comprises a rare earth metal in an amount varying between 0.0 to 2.0 wt %; preferably between 0.6 to 1.0 wt %, Typically, the rare earth metal is at least one selected from the group consisting of lanthanum, cerium, neodymium, samarium, gadolinium, yttrium and combinations thereof. Typically, the zeolite present in the FCC catalyst component is selected from the group consisting of REY, REUSY, USY, beta and combinations thereof. Typically, the FCC catalyst component comprises zeolite in an amount varying between 5 to 40 wt%; preferably between 20 to 35 wt%. Typically, the clay in the FCC catalyst component is present in an amount varying between 20-35 wt%; Typically, the zeolite present in the additive component is a medium pore size zeolite selected from the group consisting of ZSM-5, ZSM-11, ZSM-23 zeolite and combinations thereof. Typically, the additive component comprises zeolite in an amount varying between 20 to 55 wt %; more preferably between 30 to 55 wt %. Typically, the additive component further comprises phosphorous; the amount of phosphorous being in the range of 4 to 16 wt % . Typically, the clay in the additive component is present in an amount varying between 15 to 30 wt % Typically, the binder in the FCC catalyst component comprises an acid treated alumina, colloidal silica and combinations thereof. Typically, the binder in the additive component comprises at least one ingredient selected from the group consisting of phosphorus treated clay, an acid treated alumina and silica. Typically, the binder in the FCC catalyst component is present In an amount varying between 5 to 40 wt%; more preferably between 5 to 30 wt% . Typically, the binder in the additive component is present in an amount varying between 5 to 25 wt %. Typically, the alumina is selected from the group consisting of amorphous gel, aluminum trihydride, psuedoboehmite alumina, gamma alumina and mixtures thereof. Typically, the clay is at least one selected from the group consisting of kaolin and halloysite. Typically, the ratio of the proportion of the FCC catalyst and proportion of the additive component varies between 1.5 to 20 wt%. In accordance with the present invention, there is provided a process for the preparation of a catalyst for Fluid Catalytic cracking process , comprising : 1. preparing a FCC catalyst component by (a) preparing an aqueous homogenous slurry comprising : zeolite 5 to 40 wt %, binder 5 to 40 wt %, clay 10 to 40wt%and an alkaline earth metal precursor 0.01 to 0.2 wt %; all proportions being with respect to the weight of the FCC catalyst component; (b) subjecting the homogenous slurry to spray drying to obtain microsphere particles; (c) dispersing spray dried microsphere particles in a mixture of rare-earth metal salts to obtain rare-earth metal exchanged microsphere particles; and (d) subjecting the rare-earth metal exchanged microsphere particles to calcination to obtain a dry FCC catalyst component; II. preparing an additive component by (a) preparing an aqueous homogenous slurry comprising: zeolite selected from the group consisting of zeolite and phosphate stabilized zeolite 20 to 55 wt %, binder 0 to 40 wt % and an alkaline earth metal precursor 0.01 to 2.0 wt %; all proportions being with respect to the weight of the additive component; (b) subjecting the homogenous slurry to spray drying to obtain microsphere particles; and (c) subjecting the spray dried microsphere particles to calcination to obtain dry additive component; and III. admixing the independently prepared FCC catalyst and additive components to obtain a catalyst for Fluid Catalytic cracking process. Typically, the method step of the preparation of the homogenous slurry comprises the step of preparing the aqueous slurries of each of the ingredients independently and admixing them under vigorous stirring. Typically, the zeolite employed in the step of preparing a FCC catalyst component is selected from the group consisting of REY, REUSY, USY and combinations thereof. Typically, the rare earth metal is at least one selected from the group consisting of lanthanum, cerium, neodymium, samarium, gadolium, yttrium and combinations thereof. Typically, the binder employed in the step of preparing a FCC catalyst component is at least one selected from the group consisting of an organic acid treated alumina, colloidal silica and combinations thereof. Typically, the zeolite employed in the step of preparing an additive component is selected from the group consisting of ZSM-5, ZSM-11, ZSM-23 and combinations thereof. Typically, the zeolite employed in the step of preparing an additive component is stabilized with a phosphorus source. Typically, the phosphorous is at least one selected from the group consisting of phosphoric acid, mono ammonium dihydrogen phosphate, diaamonium hydrogen phosphate triammonium phosphate and mixtures thereof. Typically, the binder employed in the step of preparing an additive comprises at least one ingredient selected from the group consisting of clay, phosphorus treated clay, acid treated alumina, colloidal silica and combinations thereof. Typically, the alkaline earth metal in the FCC catalyst and additive components is introduced during their preparation. Typically, the alkaline earth metal is impregnated onto spray dried FCC catalyst and additive component. Typically, the alkaline earth metal is at least one selected from the group consisting of calcium, magnesium, strontium; preferably calcium. Typically, the ratio of the proportion of the FCC catalyst component and proportion of the additive component varies in the range of 1.5 to 20 wt%. DETAIL DESCRIPTION OF THE INVENTION Accordingly, the present invention envisages a FCC catalyst, an additive and respective methods of preparation thereof. The present invention also envisages their subsequent application for the cracking of a hydrocarbon feedstock containing hydrocarbons of higher molecular weight and higher boiling point and/or olefinic gasoline naphtha feedstock for producing lower yield of fuel gas without affecting the conversion and yield of general cracking products such as gasoline, propylene and C4 olefins. The present invention is more directed towards envisaging the effect of an alkaline earth metal on lowering additional production of fuel gas during the catalytic cracking process of the hydrocarbon feedstock with out affecting the yield of general cracking products, thereby providing a feasibility of processing the inferior quality hydrocarbon feedstock containing hydrocarbons of higher boiling point with reduced production of fuel gas. Cracking of the hydrocarbonaceous feedstock is carried out in the presence of the FCC catalyst alone or in the presence of an admixture comprising the FCC catalyst and an additive component. The employment of the additive component with the FCC catalyst is known to booster the product selectivity of the FCC catalyst. Accordingly, the present invention envisages a cracking process of a higher boiling petroleum feedstock in the presence of a FCC catalyst admixed with an additive component, prepared in accordance with the present invention. The additive component as used herein is a LPG booster additive designed and formulated particularly to reduce the additional production of the dry fuel gas during the catalytic cracking process. The FCC catalyst and the additive component of the present invention employed in the cracking of higher boiling petroleum feedstock may be present in the same catalyst particles (referred herein as integral catalyst) or in different catalyst particles. In the former case, the additive component is incorporated during the preparation of the FCC catalyst whereas in the later case, the FCC catalyst anq the additive components are prepared separately, and admixed together during cracking process. However, the integral catalyst comprising the FCC catalyst and the additive component in the same catalyst particle are found to suffer from reduced activity compared to the catalyst comprising the FCC catalyst and the additive combonent in different particles. In accordance with the present invention, the FCC catalyst and the additive component are present in separate catalyst particles wherein both combinents are prepared separately and admixed together in a pre-determined ratio during the catalytic cracking process of the higher boiling petroleum feedstock. As used herein the terms "FCC catalyst" and "FCC catalyst component" are to be used interchangeably to encompass one another and should not be construed in limiting sense-As used herein the terms "A catalyst for Fluid Catalytic Cracking (FCC) process" and "a catalyst for cracking of higher boiling petroleum feedstock" are to be used interchangeably to encompass one another and should not be construed in limiting sense and these terms refers to an admixture comprising a FCC catalyst/FCC catalyst component and an additive component. The FCC catalyst and the additive component of the present invention comprise zeolite and non-zeolite matrix. The non-zeolite matrix typically comprises an inorganic oxide that includes but is not limited to an alumina, silica, alumina-silica, and mixture thereof. The non-zeolite matrix also includes one or more of various known clays. The non-zeolite matrix as incorporated in the FCC catalyst and additive component is known to perform the function of a binder, filler or a support. The non-zeolite matrix as used in the present invention typically performs the function of a binder. Other than zeolite and non-zeolite matrix, the FCC catalyst and the additive component of the present invention further comprises an alkaline earth metal as an active component. As mentioned earlier, the catalyst used for cracking of higher boiling petroleum feedstock of the present invention is typically an admixture of the FCC catalyst and the additive component, wherein each of said components is prepared separately. In accordance with a first aspect of the present invention, there is provided a process for the preparation of a FCC catalyst; said process comprising the following steps: 1. preparing an aqueous homogenous slurry comprising zeolite, clay, binder and an alkaline earth metal precursor; 2. subjecting the homogenous slurry to spray drying to obtain microsphere particles; 3. dispersing said spray dried microsphere particles in a mixture of rare earth metal salts to obtain rare-earth exchanged microsphere particles: and 4. subjecting said rare-earth exchanged microspheres particles to calcination to obtain dry micropsheres of the FCC catalyst. The designing and formulation of the additive component carried out in a very special manner establishes certain physical properties to the additive component; the additive component prepared in a special manner having certain physical properties, when used in combination with the FCC catalyst, an unexpected shift in product composition is observed as compared to the same process carried out by using the FCC catalyst alone or with a different catalyst additive. Therefore, altogether a different approach has been adapted by the inventors of the present invention for the preparation of the additive component so as to provide certain different physical properties to it. In accordance with another aspect of the present invention, there is provided a process for the preparation of an additive component; said process comprising the following steps: 1. preparing an aqueous homogenous slurry comprising a zeolite selected from the group consisting of zeolite, and phosphate-stabilized zeolite, binder and an alkaline earth metal precursor; 2. subjecting the homogenous slurry to spray drying to obtain microsphere particles; and 3. subjecting said spray dried microspheres particles to calcination to obtain dry microsphere particles of the additive component. The zeolite employed in the preparation of the FCC catalyst of the present invention is a large pore size zeolite (pore size greater than 7A°) selected from the group consisting of USY, REUSY, RE and combinations thereof. In accordance with one of the embodiments of the present invention, the zeolite of the FCC catalyst is a USY zeolite of high hydrothermal stability; silica/alumina ratio of said USY zeolite typically ranges in between 5 to 7.2. Typically, the proportion of the zeolite in the FCC catalyst varies between 5 to 60 wt %; preferably between 5 to 40 wt % and the most preferably betwwen 20 to 35 wt%, based on the total weight of the FCC catalyst. In contrast to the large pore size zeolite employed in the preparation of the FCC catalyst, the additive component of the FCC catalyst preferably comprises a medium pore size zeolite (pore size in the range of 5 to 6 A0). The smaller size of the zeolite present in the additive component facilitates the selective cracking of linear hydrocarbon to lighter olefins. In accordance with the present invention, the medium pore size zeolite employed in the preparation of the additive component is selected from the group consisting of ZSM-5, ZSM-1L ZSM-23 and combinations thereof. Typically, the amount of medium pore size zeolite in the additive component is in the range of 5 to 60 wt %; preferably in the range of 20 to 55 wt %, and most preferably in the range of 30 to 55 wt%. The stabilization of the medium pore size zeolite, particularly ZSM-5 with a phosphorous containing compound is believed to promote the product selectivity and stability of the resultant catalyst. Therefore, the medium pore size zeolite present in the additive component of the present invention is stabilized with a phosphorous containing compound prior to its use in the preparation of the additive component. In accordance with one of the embodiments of the present invention, the medium pore size zeolite is treated with a phosphorous containing compound selected from the group consisting of phosphoric acid, mono ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate and combinations thereof. Such stabilized additive component contains phosphorus in an amount of from 4 to 16 wt%, based on the total weight of the additive component, as measured by the amount of phosphate. The slurry comprising zeolite or the phosphorous-stabilized zeolite of the present invention is further treated with a binder that includes inorganic oxide materials selected from the group consisting of an alumina, silica, clay and combination thereof In accordance with one of the embodiments of the present invention, the binder employed in the preparation of the FCC catalyst is at least one selected from the group consisting of an alumina, silica and combination thereof. Typically, the amount of the binder comprising alumina, silica and combinations thereof present in the FCC catalyst is in the range of 0-40 wt %; preferably in the range of 5 to 40 wt %, and more preferably in the range of 5 to 30 wt%. In accordance with another embodiment of the present invention, the binder employed in the preparation of the additive component is at least one selected from the group consisting of an alumina, silica, clay, clay-phosphate and combinations thereof. Typically, the amount of binder comprising alumina, silica and combinations thereof in the additive component is in the range of o to 40 wt %; preferably in the range of 5 to 25 wt%. Typically, the alumina is selected from the group consisting of amorphous alumina gel, alumina trihydride, psuedobohmite alumina, gamma alumina and combination thereof. The silica used in the preparation of the FCC catalyst as well as additive component is colloidal silica having a mean diameter ranging from 4 nm to about 90 nm, and having the lowest residual soda content, below about 0.3 wt%. Prior to admixing, the inorganic binder slurry is treated with an acid selected from the group consisting of mineral acid and organic acid that includes but is not limited to a nitric acid, formic acid, acetic acid and combinations thereof. However, the organic acids are the preferred acids in place of the mineral acids as the residues of the mineral acids such as chloride, sulphate and nitrate radicals present in the zeolite lattice may be hazardous to the hardware as well as to the environment. The proportion of the clay and/or phosphorous treated clay employed in the preparation of the FCC catalyst and the additive component of the present invention varies between 10-40 wt%, based on the weight of the FCC catalyst and additive components independently. In accordance with one of the embodiments of the present invention, the amount of clay present in the FCC catalyst varies between 20 to 35 wt%, based on the total weight of the FCC catalyst. In accordance with another embodiment of the present invention, the amount of clay, phosphorous treated clay and combinations thereof present in the additive component varies between 15 to 30 wt%, based on the total weight of the additive component. Process step of the preparation of the homogenous slurry comprises a method step of preparing the aqueous slurries of each ingredient independently and ad-mixing them under vigorous stirring. Admixing of the slurries follows no definite order. The ingredient slurries can be mixed in any order. In accordance with one of the embodiments of the present invention, the aqueous slurries of each independent ingredient are mixed in the order of clay, silica, alumina, and then zeolite. In accordance with another embodiment of the present invention, the aqueous slurries of each independent ingredient are mixed in the order of clay, silica, zeolite, and then alumina. In accordance with a still another embodiment of the present invention, the aqueous slurries of each independent ingredient are mixed in the order of clay, alumina, zeolite, and then silica, In accordance with a yet another embodiment of the present invention, the aqueous slurries ot each independent ingredient are mixed in the order of silica, alumina, zeolite, and then clay. The inclusive and through research in to cracking catalyst designing, carried out by the inventors of the invention is aiming to develop a FCC catalyst and an additive that reduces the additional production of dry fuel gas during the catalytic cracking process of the hydrocarbon feedstock. In light of the above specified objects,, the inventors of the present invention have designed an alkaline earth metal incorporated FCC catalyst and additive, and their subsequent application in the cracking of the hydrocarbon feedstock, more particularly an inferior quality feedstock comprising hydrocarbons of higher boiling point. The alkaline earth metal can be introduced during the preparation of the FCC catalyst and the additive component. Alternatively it can be impregnated onto spray dried FCC catalyst and additive component. In accordance with one of the embodiments of the present invention, the alkaline earth metal in the FCC catalyst and additive component is introduced during their method step of preparation. In accordance with another embodiment of the present invention, the alkaline earth metal is impregnated on to spray dried FCC catalyst and additive component. The alkaline earth metal precursor used in the preparation of the FCC catalyst and additive component is typically a salt of alkaline earth metal that includes but is not limited to nitrates, sulfate, phosphate, carbonate or hydroxides prepared from the salt. In accordance with the present invention, the salt of the alkaline earth metal is selected from group consisting of salt of calcium, magnesium, strontium and combinations thereof; preferably of calcium metal. Typically, the proportion of the calcium present in the FCC catalyst varies between 0.01 to 2.0 wt%, based on the weight of the FCC catalyst. Typically, the proportion of the calcium present in the additive component varies between 0.01 to 2.0 wt%, based on the weight of the additive component. The homogeneous slurry thus obtained after admixing the aqueous slurries of each ingredient under vigorous stirring comprising a zeolite or phosphate stabilized zeolite, silica, alumina, clay, and optionally an alkaline earth metal precursor is further subjected to a spray dry process. The spray dry process of the homogenous slurry provides the microsphere particles of each of said components independently. The obtained microsphere particles of each of said components are further subjected to calcination at a temperature of 500 °C for a period of 1 hour to obtain dry microsphere particles of each of said components independently. The large pore size zeolite present in the FCC catalyst of the present invention is preferably a rare earth metal exchanged zeolite. The rare earth metal exchange step can be performed either prior the preparation of the FCC catalyst or can also be performed later onto spray dried microsphere particles of the FCC catalyst. In accordance with the present invention, the spray dried microspheres particles of the FCC catalyst are further subjected to a metal exchange process step wherein the spray dried FCC catalyst is dispersed in a mixture of rare earth metal nitrate solution at elevated temperature of 70 °C to 90 °C for a period of 30 -60 minutes. The rare earth metaj salts employed for the metal exchange process are typically selected from the group that includes but is not limited to nitrates of lanthanum, cerium, neodymium, samarium, gadolinium and yttrium or combination thereof. Upon completion of the exchange process, the rare earth metal exchanged microsphere particles of the FCC catalyst are washed with water to remove the excess of nitrates present therein. Prior to rare earth exchange, the spray dried microsphere particles of the FCC catalyst are exchanged with ammonium ions (NH4NO3 or NH4SO4). Typically, the amount of a rare earth metal oxide present in the FCC catalyst varies between 0.5 to 2.0 wt%; preferably between 0.6 to 1.0 wt%, based on the total weight of the FCC catalyst. The FCC catalyst and the additive component obtained by the process of the present invention are having an average particle size in the range of 70-100 microns with an attrition index in the range of 3-5. The FCC catalyst and the additive component, as described herein, has a particular application for the cracking of the hydrocarbon feedstock and/or olefinic gasoline naphtha feed stock for producing lower yield of fuel gas without affecting the general yield pattern of the cracking products such as gasoline propylene, LPG, more particularly LPG. The FCC catalyst and the additive component thus obtained independently by the process of the present invention are further hydrothermally deactivated at a temperature of 800 °C to 820 °C using 100 % steam at atmospheric pressure. As mentioned earlier, the catalyst employed for the cracking of higher boiling petroleum feed stock in accordance with the present invention is an admixture of the FCC catalyst and additive component. The FCC catalyst and the additive component of the present invention are admixed in a pre-determined weight ratio in a fixed fluid bed microreactor. The admixture of the hydrothermally deactivated FCC catalyst and additive is allowed to contact with higher boiling petroleum feedstock at reaction conditions suitable for cracking of hydrocarbonaceous feedstock. Typically, the ratio of proportion of the FCC catalyst and the proportion of the additive varies in the range of 1.5 to 20. The microreactor of the present invention is electrically heated to maintain the cracking catalyst bed temperature typically at 540 °C. To generate cracking data at various catalyst/oil ratio (4:10), the hydrotreated Vacuum Gas Oil (VGO) is injected in the fluidized bed for 30 seconds. The admixture of the FCC catalyst and the additive of the present invention prepared in accordance with the process of the present invention are efficient to decrease the fuel gas production without affecting the yield pattern of general cracking products such as LPG, light olefins and gasoline. Typically, the catalyst for FCC process comprising the admixture of the FCC catalyst and additive in pre-detetmined weight ratio reduces fuel gas production in the range of 20 to 60 % during the catalytic cracking process of a hydrocarbon feedstock. The present invention is further illustrated with reference to the following examples which are to be regarded solely as illustration and not as limiting the scope of the present invention. EXAMPLE 1 Example 1 describes the process for the preparation of a FCC catalyst 333 g of Pural SB grade pseudoboehmite alumina (having loss of ignition of 24 wt %) was mixed with 533 g of demineralized (DM) water. To this 71 g of acetic acid (100% concentration) was added to peptise the alumina. To the peptized alumina slurry, 1667 g of colloidal silica \vas added. In a separate step, 824 g of kaolin clay (having loss on ignition 15 wt%) was mixed with 824 g of DM water under vigorous stirring to obtain clay slurry. To the obtained clay slurry, the silica-alumina slurry was added and stirred vigorously to obtain a homogenous mixture. In a separate process step, 7778 g of ammonium USY zeolite (loss on ignition 10 wt%) having silica to alumina molar ratio of 5.2-7.2 was made into a slurry with 7778 g of DM water and milled to a fine paste to produce a zeolite slurry. The obtained zeolite slurry was then mixed with the clay-silica-alumina slurry for 30 min under vigorous stirring to obtain homogenous slurry. The homogenous slurry was spray dried to get microsphere particle of the FCC catalyst with Average Particle Size (APS) in the range of 70-100 microns. Spray dried catalyst was calcined at 500 °C for 1 hr. The measured ABD and attrition index (ASTM D5757) is 0.78 g/cc and 3 respectively. 200 g of calcined FCC catalyst was exchanged with solution containing Rare earth nitrate salt at temperature of 70-80 °C for 1 hour. The RE exchanged material was washed with hot water to remove excess of nitrate salts and dried overnight at 120 °C followed by calcinations at 500 °C for 1 h. The product contains 0.54 wt% REO and 0.28 wt% Na20. Calcium was impregnated on the FCC catalyst using Ca naphthenate salt. The calcium impregnated FCC catalyst was then hydrothermally deactivated at a temperature of 800 °C for 20 hrs using 100% steam, at atmospheric pressure before performing the cracking reaction. The FCC catalyst thus prepared was characterized by various physico-chemical techniques. The physico-chemical properties of the FCC catalyst of the present invention are tabulated in Table -1. The particle size distribution, attrition index suggest that the said prepared catalyst is suitable for use in commercial FCC unit. Table-1: Physico-Chemical Properties of the FCC catalyst (without calcium) Catalyst component Catalyst component without calcium Surface area. m2/grn Total Surface Area (TSA) 336 Zeolite Surface Area (ZSA) 226 Chemical analysis, wt % AI2O3 29.37 Na20 0.28 P2O5 0.0 Re203 0.54 Particle size distribution, % < 20 micron 0 <40 micron 4 < 80 micron 67 APS, micron 71 Attrition Index (ASTM D5757) (wt % loss in 5 hrs) 3 Table-2 of the present invention summarizes the total catalyst surface area, acidity and pore volume on the effect of calcium in the FCC catalyst. Table 2: Pore Volume and Acidity of calcium impregnated catalyst Parameters Catalyst (Steamed) Calcium, wt% 0 1 0.5 1.0 Total surface area, m /gm 165 149 137 Zeolite surface area, m2/gm 107 107 92 Zeo\ite ?ore volume, cclgm 0.049 0.049 0.041 Total Pore volume, cc/gm 0.203 0.187 0.180 Total pore volume reduction, % Base 7.9 11.3 Total acidity, mmol/gm 0.044 0.044 0.036 Acidity reduction, mmol/gm Base Nil 18 From the Table-2, Total Surface Area (TSA) of catalyst reduces to 137 m2/gm from 165 m2/gm with increase in calcium level from 0.0 wt% to 1 vvt%. However, there is no drop in total acidity up to 0.5 wt%, but it reduces marginally when calcium level on catalyst is increased to 1.0 wt%. This is because there is no change in Zeolite Surface Area (ZSA) up to 0.5 wt% calcium. Acidity drops thereafter as ZSA is affected by increasing calcium level at 1.0 wt%. Moreover, it is interesting to note that Total Pore Volume (TPV) drops to 0.187 cc/gm from 0.203 cc/gm by changing calcium from 0.0 wt% to 0.5 wt%. This reduction is mostly due to reduction of matrix pore volume. This means matrix pore is partially filled by calcium at lower level of calcium. However, at higher level of calcium lwt%, both matrix and micropore are partially filled with calcium as TPV is dropped to 0.180 cc/gm by increasing calcium level to lwt%. EXAMPLE 2 Example 2 illustrates the process for the preparation of an additive component of the FCC catalyst. 1110 g of ZSM-5 zeolite (loss on ignition 10 wt%) having silica to alumina molar ratio of 30 was made into a slurry with 1200 g of DM water and milled to a fine paste to produce a zeolite slurry. Mono ammonium dihydrogen phosphate (2872 g) was dissolved in 4830 g of DM water and mixed with ZSM-5 zeolite slurry under constant stirring to obtain phosphate stabilized zeolite. In a separate step, 131 g of Pural SB grade alumina (having loss of ignition of 24 wt %) was mixed with 431 g of demineraized (DM) water to obtain alumina slurry which was further peptized with 10 g of formic acid. Similarly, 424 g of kaolin clay (having loss on ignition 15 wt%) was made into a slurry with 338 g of DM water and kept under vigorous stirring while 23.5 g of ortho-phosphoric acid (85% concentration) was added slowly. Earlier prepared alumina gel, zeolite-phosphate slurry, clay-phosphate slurry and 1000 g of acidic colloidal silica were mixed together under vigorous stirring to obtain homogenous slurry, which was then spray dried. Spray dried product was calcined at 500 °C for I hr. The additive product was impregnated with calcium by using calcium naphthenate salt as a precursor and it is characterized for various physico-chemical properties. Physico-chemical characterization of the additive component is tabulated in Table-3. Table 3: Physico-Chemical Properties of additive component without calcium Physico-chemical properties Surface area, m2/gm Total Surface Area (TSA) 140 Zeolite Surface Area (ZSA) 110 Chemical analysis, wt % A1203 18.70 Na20 0.11 P2O5 11.9 Re303 0.0 Particle size distribution, % < 20 micron 0 < 40 micron 6 < 80 micron 53 APS, micron 77 Attrition Index (ASTM D5757) (wt % loss in 5 hrs) 3.5 From the data as tabulated in Table-3 of the present invention, it is clearly understood that all the physico-chemical properties like particle size distribution, attrition index etc. of the additive are suitable for their use in FCC unit. Table 4: Effect of calcium impregnation on Pore Volume and acidity of additive Parameters Additive (Steamed) Calcium, wt% 0 0.5 1 Total surface area, m2/gm 170 166 148 Zeolite surface area, m2/gm 93 88 77 Zeolite Pore volume, cc/gm 0.042. 0.040 0.0350 Total Pore volume, cc/gm 0.153 0.151 0.1360 Total pore volume reduction, % Base 1.3 11.10 Total acidity, mmol/gm 0.100 0.090 0.062 Acidity reduction, mmot/gm Base 10 40 From the data as provided in Table-4 of the present invention, it is clearly seen that TSA, ZSA, ZPV and TPV of the FCC additive are not changed appreciably by changing the calcium level from 0.0 to 0.5 wt%. Similarly, there is no appreciable change in the total acidity of the catalyst-additive up to 0.5 wt% of calcium. However, at 1.0 wt% of calcium, TSA reduces from 166 to 148 m2/gm, ZSA from 88 to 77 m2/gm, TPV from 0.151 to 0.136 cc/gm, and ZPV from 0.040 cc/gm to 0.035 cc/gm. Similarly, the total acidity is also reduced by 40%. EXAMPLE 3 Example 3 illustrates the performance assessment of the FCC catalyst and additive. The FCC catalyst and additive components prepared in accordance with example 1 and 2 of the present invention were hydrothermally deactivated separately at a temperature of 800 °C and at atmospheric pressure for 20 hours using 100 % steam. The admixture of the hydrothermally deactivated FCC catalyst and additive with predetermined ratio of 75:25 was loaded in a fixed fluid bed micro-reactor. The micro-reactor was electrically heated to maintain the catalyst bed temperature at 545 °C. The hydrotreated Vacuum Gas Oil (VGO) was injected in the fluidized bed for 30 seconds to generate the cracking data at various catalyst to oil ratio (Cat/Oil) (4-10). The product selectivity at a fixed conversion of 76 wt % obtained during the cracking process of the hydrocarbon feedstock carried out in the presence of FCC catalyst/ additive is tabulated in Table-5 of the present invention. Table 5: Product selectivity at conversion of 76 wt %, Parameters Base Case Ca doped case Calcium, wt% 0.5 1.0 Yield Pattern