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168., , 0, , 169,, , 170., , +Os(g) + COn(g) ; + 94.450 kcal. This is :, a) an exothermic reaction, , b) an endothermic reaction, , ©) a chain reaction, , d) a catalytic reaction, , It is a general principle that the less energy @, system contains, it is, , a) more stable b) less stable, , ©) unstable d) more unstable, , AH for the reaction, Clg, + Cligy —+ Clap will be, a) Zero b) +ve, , -ve d) », , . AH forthe reaction, Hy{g) —» H(g)+ H(g) will be, , a) Zero b) - ve, Q +ve do, Which plot represents for an exothermic reaction, , ik i >, ao vl 7, , 9 Ae \Nep 9 HR, , Time —> Time —>, Change in enthalpy is defined as, a) the change in heat content, b) the total energy change at constant pressure, and temperature, ©) the heat change at constant volume if An = 0, d) all are correct, The word ‘standard’ in standard molar enthalpy, change implies, a) Temperature 298 K, b) Pressure 1 atm, ©) Temperature 298 K and pressure 1 atm, d) All temperatures and all pressures, , , , , , , , . The Enthalpy change for the reaction,, , C(s) + 25(s) —+ CS,(1) is called, , a) Enthalpy of solution of CS,, , b) Enthalpy of fusion of CS,, , 9 Enthalpy of formation of CS,, , d) Enthalpy of combustion of carbon

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176., , 0, , 177., , 6, , 178., , 0, , 179., , ©, , 180., , 181., , The enthalpy change for the process,, , C(s) —— C(g) is known as enthalpy of, , a) Fusion b) Vaporisation, , c) Combustion d) Sublimation, , Bond energy of a molecule, , a) is always negative, , b) is always positive, , c) either positive or negative, , d) depends upon the physical state of the system, , Thermochemistry is the study of relationship, between heat energy and, , a) chemical energy _b) activation energy, , c) frictional energy _d) electrical energy, , For the reaction, 30, —-+ 20 ; AH = +ve. We can, , say that, , a) ozone is more stable than oxygen, , b) ozone is less stable than oxygen and ozone, decomposes forming oxygen readily, , c) oxygen is less stable than ozone and oxygen, readily forms ozone, , d) none, , Standard enthalpy of formation of compound is, , defined as, , a) Heat change to form one mole of the compound, from its elements, , b) Heat required to form one molecule of a, compound, , c) Change in heat content of the system when one, molecule of a compound is formed, , d) None, , The enthalpy changes of formation of the gaseous, , oxides of nitrogen (N,O and NO) are positive, , because of, , a) the high bond energy of the nitrogen molecule, , b) the high electron affinity of oxygen atoms, , c) the high electron affinity of nitrogen atoms, , d) the tendency of oxygen to form o*

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The enthalpy of formation HI is 30.4 kJ. Which, statement is false according to this observation, a) HI is an endothermic compound, , H4g)+I(g) — 2HI(g);AH= 60.8 kJ, , ¢) Hlisa stable compound, , 4) Hlis an unstable compound, , Which is NOT characteristic of thermochemical, , equation, , a) it indicates physical state of reactants and, products, , b) it indicates whether the reaction is exothermic, or endothermic, , ©) it indicates allotrope of reactants if present, , 4) it indicates whether reaction would occur or, not, , The magnitude of heat of solution ...... on addition, , of solvent to solution, , a) decreases, , b) increases, , ¢) remains constant, , d) increases or decreases, , The enthalpy of formation of water is exothermic, , in nature because, , a) H, & O, have higher temperature than water, , b) H; & O, have lower temperature than water, , ©) H, &O, have higher internal energy than water, , d) None, , Two atoms of hydrogen combine to form a, , molecule of hydrogen gas, the energy of the H,, , molecule is, , a) greater than that of separate atoms, , b) equal to that of separate atoms, , ©) lower than that of separate atoms, , d) sometimes lower and sometimes higher, , Standard enthalpy of one mole of graphite is, , @) Leal mor! b) equivalent to charcoal, , © more than diamond d) assumed as zero, , Which represents unit of R ?, , a) LatmK"! mol? b) JK"! mol, , «) caldeg*mol? —d) all, , In a chemical reaction if all reactants and, , products are in liquid state then, a) AH> AU b) AH<AU, co) AH=AU d) None, , The law of Lavoisier and Laplace is based on, , a) the principle of conservation of energy, , b) equivalence of mechanical and thermal, energies, , ¢) the principle of conservation of matter, , d) equivalence of mechanical and chemical, , energies