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Right answer is (a) 96500 C

The best I can explain: FARADAY is a unit which has no dimensions and it represents electric charge quantity. In the International System of units, it’s coulombs. 1 Faraday is equal to 96500 coulombs. F represents Faraday constant.

Correct CHOICE is (c) equilibrium constant

The best I can explain: In the above equation ΔG = – 2.303 RT logK, G is the change in standard Gibbs free energy, R is the universal gas constant, T is TEMPERATURE, K is the equilibrium constant while LOG stands for the logarithm of base 10.

Correct ANSWER is (a) ΔG = -nFEcell

Easy explanation: The RELATION between Gibbs free ENERGY and EMF of the cell is ΔG = -nFEcell, where G is the caps free energy and as a number of electrons lost or gained while f depicts Faraday and E cell STAND for standard electrode POTENTIAL.

The correct choice is (a) 163 kJ/mol

Explanation: The chemical EQUATION for the conversion of oxygen to Ozone is 3/2O2 → O3. We have the equation, ΔG = – 2.303 RT LOG KP. So by SUBSTITUTING we get ΔG = – 2.303 x 8.314 J/K-mol x 293K x 2.47 x 10^-29 = 163000 J/mol = 163 kJ/mol.

Right choice is (b) low temperature

Explanation: When a CHANGE in entropy and the change in enthalpy are positive the GIBBS FREE energy is positive at low TEMPERATURES and negative at HIGH temperatures. We can obtain this through the equation ΔG = ΔH – TΔS.

Right choice is (d) photosynthesis

To explain: A reaction that is spontaneous and favorable is known as an exergonic reaction, it RELEASES energy into the surroundings. The system’s FREE energy decreases here. The GIBBS free energy of an exergonic reaction is NEGATIVE.

The correct answer is (a) endergonic

To explain: An unfavorable REACTION or a nonspontaneous reaction that requires more energy than we get from that reaction is called endergonic reaction. It OBSERVES heat from SURROUNDINGS and the change in ENTROPY decreases it is ALSO a type of endothermic reaction.

Correct OPTION is (a) 3.4 kcal

Explanation: Using the EQUATION ΔG = ΔH – TΔS, where G is represented by the Gibbs free energy, H is represented by the CHANGE in enthalpy, T is represented by the temperature and S is represented by the entropy. ΔH = ΔG + TΔS = 3.4 kcal – 293 x 2.4 cal/K = 3.4 kcal.

Right ANSWER is (d) -7.3 Kcal

To EXPLAIN: We have ΔG = ΔH – TΔS; by SUBSTITUTING ΔH = 19.07 kcal and ΔS = 90 cal/K, we get ΔG = 19.07 Kcal – 293(90 cal/K) = 19.07 Kcal – 26.37 Kcal = -7300 cal = -7.3 Kcal. The Gibbs FREE energy CHANGE is -7.3 Kcal.

The correct option is (a) ΔS(system) + ΔS(surroundings) > 0

For EXPLANATION I WOULD SAY: ΔS(universe) > 0 can also be written as ΔS(system) + ΔS(surroundings) > 0, as the universe is nothing but the system and surroundings. The above mentioned CONDITION is used when a reaction is at equilibrium.

Correct answer is (B) first LAW of thermodynamics

For explanation I would say: The second law of thermodynamics is given as the entropy of the universe is always increasing in the course of every spontaneous or NATURAL CHANGE also can be SAID as the heat cannot flow itself from a colder to a hotter body.

Right option is (a) true

The explanation: We can define the THIRD law of thermodynamics ENTROPY of a perfectly crystalline substance at zero kelvin or absolute zero is taken to be zero, but this is not APPLICABLE if there is any IMPERFECTION at 0 k, the entropy will be larger than 0.

The CORRECT option is (c) LESS than zero

Explanation: A reaction is spontaneous if Gibbs free ENERGY is less than zero and the reaction is nonspontaneous if the Gibbs free energy is GREATER than zero. The reaction is at equilibrium STATE if gives free energy is equal to zero.

The CORRECT choice is (a) it is positive

To elaborate: According to the Helmholtz equation; G = H -TS, when enthalpy H is positive and entropy S is negative, the GIBBS free energy is always positive and the REACTION is not spontaneous at all temperatures.

Correct option is (B) extensive

Explanation: Entropy is a measurement of RANDOMNESS or disorder of MOLECULES it is a state function as WELL as an extensive property. Its units are J/K-mole. Extensive property depends on the SIZE and quantity of the mass.

The correct answer is (b) melting of IRON

To explain I would say: A physical or chemical process which occurs by its on in a particular direction under a particular set of conditions without any force is KNOWN as a spontaneous process and it cannot be reversed. Here melting of iron is only POSSIBLE when we SUPPLY a large amount of heat so it is not a spontaneous process.

The correct choice is (a) dependent

Easiest explanation: Enthalpy of dilution is the enthalpy change when 1 mole of a SUBSTANCE is diluted from ONE concentration to another. So it is dependent on your original concentration of the solution and the AMOUNT of solvent ADDED.

Right answer is (a) negative

Easy explanation: Enthalpy change when 1 mole of a substance is dissolved in a large excess of solvent so that on further delusion no APPRECIABLE heat change occurs, is KNOWN as enthalpy of solution. It can EITHER be positive or negative DEPENDING on the reaction, whether it is exothermic or ENDOTHERMIC.

The CORRECT ANSWER is (b) BORN Haber cycle

To EXPLAIN: An indirect method, in which we can construct an enthalpy diagram is CALLED a Born-Haber cycle as it is nearly impossible to determine lattice enthalpies directly by experiment. It is an approach to analyze reaction energies.

Right answer is (c) formation of a water molecule

To explain: The ENTHALPY of atomization is an enthalpy change that occurs when one molecule of a molecule BREAKS into its atoms, but here the of a water molecule formation does not SATISFY the definition of the enthalpy of atomization.

Correct CHOICE is (a) lattice energy

Easiest explanation: Lattice enthalpy is the enthalpy CHANGE when one molecule of an ionic COMPOUND DISSOCIATES into its IONS and gaseous state. Here sodium chloride is an ionic compound and it decomposes into sodium and chloride ions, so the energy released is lattice energy.

Right option is (d) 598 KJ/MOL

Easiest explanation: By following the rule ΔHr = Σ ΔHf[products] – ∑ ΔHf[reactants], we get -(x + 4(412) + 432) + (348 + 6(412)) = -138 KJ/mol; x = 598 KJ/mol. So the CARBON carbon DOUBLE bond energy in Ethane is given as 598 KJ per Mol.

Right OPTION is (a) BOND DISSOCIATION enthalpy

For explanation: In case of the decomposition of hydrogen molecule the enthalpy is the same as enthalpy of atomization as well as bond dissociation enthalpy because the bond association enthalpy refers to the breakage of H-H Bond. So that TWO hydrogen atoms are formed whereas enthalpy of atomization is the breakage of hydrogen molecules in ORDER to form two atoms.

Right choice is (a) True

To explain I would SAY: The enthalpy CHANGE that occurs when one mole of a molecule breaks into its atoms is KNOWN as enthalpy of atomization. The energy released during the CONVERSION of a HYDROGEN molecule into two hydrogen atoms is enthalpy of atomization.

Right OPTION is (a) TRUE

Best explanation: The EQUATION ΔHr = Σ ΔHf[products] – Σ ΔHf[reactants] says that the enthalpy of a reaction is the DIFFERENCE between the enthalpy of products and enthalpy of reactants. The above statement regarding enthalpy is true.

Right OPTION is (B) negative

The EXPLANATION: Enthalpy of combustion is the enthalpy change that takes PLACE when one mole of a compound undergoes complete combustion in the presence of oxygen. It is represented by ΔHc, it is always negative because the PROCESS of combustion is exothermic.

The correct answer is (c) determination of Gibb’s energy

Explanation: The following are the applications of Hess’s LAW; determination of heat of FORMATION, determination of heat of transition and determination of heat of HYDRATION, ALSO to CALCULATE bond energies.

The correct choice is (b) KJ per Mol

To explain: The enthalpy change that OCCURS during melting of one mole of a solid SUBSTANCE in the standard state is called standard enthalpy of fusion or MOLAR enthalpy of fusion, it is represented by the symbol ΔfusH^–, the UNITS of this are KJ per Mol.

The CORRECT choice is (c) number of moles

The EXPLANATION is: In a balanced thermochemical equation, the coefficients always REFER to the number of the moles (but never molecules) of reactants and products involved in a REACTION so 2 in the COEFFICIENT of H2O refers to the number of the moles of water.

Right option is (a) TRUE

To explain I WOULD say: For example, the formation of AMMONIA has an enthalpy of -91.8 KJ per MOLE and the decomposition of ammonia has an enthalpy of + 91.8 KJ per Mol. So the above statement that when a chemical reaction is reversed the value of enthalpy is reversed in the sign is true.

Correct ANSWER is (d) 1.506 KJ

Easy explanation: We know that Q = msΔT, where Q is the energy,m is the mass of WATER, s is the specific HEAT of water and T is the temperature. So the change in energy REQUIRED here = 18 g x 4.184 J/g-K x 20K = 1.506KJ.

Correct choice is (d) 41.53 KJ/mol

Best EXPLANATION: HEAT required to eliminate water : n x ΔvapH^– = (1 mol) × (44.01 kJ mol^–1) = 44.01 kJ mol^-1. Δvapor = ΔvapH – ΔnRT = 44.01 kJ mol^-1 – 1×8.314 J/K-mol x 298 k x 10^-3 = 41.53 KJ/mol. So the amount of energy NEEDED is 41.53 KJ/mol.

The correct answer is (d) 50 UNITS

Explanation: We know thatΔH = ΔU + PΔV; ΔH is the enthalpy, ΔU is the internal energy, ΔV is the CHANGE in volume and P is the PRESSURE. So by SUBSTITUTING the enthalpy, internal energy during a process and change in volume as 500 units, 400 units and 2 units, we get pressure as 50 units.

Right ANSWER is (b) 8.34 KJ/Kg-k

The best I can explain: The formula of heat ENERGY is GIVEN by the EXPRESSION: Q = mcΔT, m is the mass of the substance, c is the specific heat CAPACITY and ΔT is the temperature difference. c = Q/mΔT; c = 100KJ/3kg(4k) = 8.34 KJ/Kg-k.

Right option is (c) 2260 KJ

For EXPLANATION: The latent HEAT of VAPORIZATION of water is 2260 KJ/Kg. The heat that is REQUIRED to convert water at 373 K to steam is given by Q = mL, where m = mass of the water and L = latent heat vaporization of water; heat energy required = 1 kg x 2260 KJ/Kg = 2260 KJ.

Correct answer is (a) 0

To ELABORATE: During an adiabatic PROCESS the change in TOTAL energy is ZERO, As we know that the specific heat capacity is given by the total heat required by mass X change in temperature, heat energy is zero the specific heat capacity becomes zero.

The correct answer is (c) infinity

For explanation I would SAY: During the phase CHANGE of a substance the temperature change is zero. As we KNOW that specific heat CAPACITY = Q/cΔT which is zero; specific heat capacity becomes infinity, so during the process of conversion of ice into the WATER, the specific heat capacity is infinity.

Correct ANSWER is (B) heat of combustion

Easiest explanation: A bomb calorimeter is used to measure the heat of combustion of a reaction. It has to withstand a large amount of PRESSURE, in ORDER to determine the heat of combustion. It is an isochoric process and the heat energy is EQUAL to the internal energy.

The correct CHOICE is (a) CV

To explain I WOULD say: A BOMB calorimeter operates at a constant volume i.e. it is an isochoric process. So the heat capacity is CV which represents heat capacity at constant volume. While CP represents heat capacity at constant PRESSURE.

The correct option is (a) increases

Easiest EXPLANATION: In a Bomb calorimeter, the reaction occurs in a vessel and that is SURROUNDED by the water bath. If it is an exothermic reaction the TEMPERATURE rises and if it is an endothermic reaction the temperature decreases. Temperature can be MEASURED USING a thermometer.

Correct CHOICE is (b) isochoric

To elaborate: ABomb calorimeter works at CONSTANT volume, so it is isochoric in nature. Here, the heat energy that’s measured is only the internal energy. The WORK done is zero because of no change in volume.