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InterviewSolution
This section includes InterviewSolutions, each offering curated multiple-choice questions to sharpen your knowledge and support exam preparation. Choose a topic below to get started.
| 151. |
For a hypothetic reaction `ArarrB`, the activation energies for forward and backward reactions are 19 kJ/mole and 9 kJ/mole respectively. The heat of reaction isA. 28 kJB. 19 kJC. 10 kJD. 9 kJ |
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Answer» Correct Answer - C `DeltaH=E_(a)` for forward reaction `-E_(a)` for backward reaction = 19-9=10 kJ. |
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| 152. |
Enthalpy of formation of two compounds x and y are - 84 kJ and - 156 kJ respectively. Which of the following statement is correctA. x is more stable than yB. x is less stable than yC. Both x and y are unstableD. x and y are endothermic compounds |
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Answer» Correct Answer - B The compound Y possess less energy than the X and thus Y is more stable than X. |
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| 153. |
A cylinder of gas is assumed to contain 11.2 kg of butane `(C_(4)H_(10))`. If a normal family needs 20000 kJ of energy per day. The cylinder will last: (Given that `DeltaH` for combustion of butane is -2658 kJ)A. 20 daysB. 25 daysC. 26 daysD. 24 days |
| Answer» Correct Answer - C | |
| 154. |
`DeltaH_(f)^(@)` (298 K) of methanol is given by the chemical equationA. `CH_(4)(g)+1//2O_(2)(g)rarrCH_(3)OH(g)`B. `C("graphite")+1//2O_(2)(g)+2H_(2)(g)rarrCH_(3)OH(l)`C. `C("diamond")+1//2O_(2)(g)+2H_(2)(g)rarrCH_(3)OH(l)`D. `CO(g)+2H_(2)(g)rarrCH_(3)OH(l)` |
| Answer» Correct Answer - B | |
| 155. |
An exothermic reaction is one whichA. Takes place only on heatingB. Is accompanied by a flameC. Is accompanied by a absorption of heatD. Is accompanied by evolution of heat |
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Answer» Correct Answer - D In exothermic reactions heat is evolved. |
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| 156. |
In a closed insulated container, a liquid is stirred with a paddle to increase its temperature. In this process, which of the following is trueA. `DeltaE=W=Q=0`B. `DeltaE ne0,Q=W=0`C. `DeltaE=W ne 0, Q=0`D. `DeltaE = Qne0, W=0` |
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Answer» Correct Answer - C As the system is closed and insulated no heat enter or leave the system, i.e. q = 0 , `thereforeDeltaE = Q+W=W`. |
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| 157. |
During an isothermal expansion of an ideal gas itsA. Internal energy increasesB. Enthalpy decreasesC. Enthalpy remains unaffectedD. Enthalpy reduces to zero |
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Answer» Correct Answer - C During isothermal expansion of idea gas, `DeltaT=0` `DeltaH=DeltaE+PDeltaV=DeltaE+nRDeltaT=0+0=0`. |
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| 158. |
At `27^(@)C`, one mole of an ideal gas is compressed isothermally and reversibly from a pressure of 2 atm to 10 atm. The values of `DeltaE` and q are (R=2)A. `0, -965.84 cal`B. `-965.84 cal, + 965.84 cal`C. `+ 865.58 cal, -865.58 cal`D. `-865.58 cal, -865.58 cal` |
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Answer» Correct Answer - A `W=2.303 nRTlog.(P_(2))/(P_(1))=2.303xx1xx2xx300log.(10)/(2)=965.84` at constant temperature, `DeltaE=0` `DeltaE=q+w=40-8=32 J` |
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| 159. |
6 moles of an ideal gas expand isothermally and reversibly from a volume of 1 litre to a volume of 10 litres at `27^(@)C`. What is the maximum work doneA. 47 kJB. 100 kJC. 0D. 34.465 kJ |
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Answer» Correct Answer - D Workdone in isothermal reversible expansion `W=PDeltaV` `W=-2.303 nRTlog.(V_(2))/(V_(1))` `=-2.303xx6xx8.314xx300log.(10)/(1)` =34464.8 Joule = 34.465 kJ. |
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| 160. |
When you freeze water in your freezer to make ice cubes, the amount of order in the molecules of water increases. However, second law of thermodynamics says that the amount of order in an isolated system can only stay constant or decrease with time. How can this making of ice violates second lawA. Because water expands during ice formationB. Because ice formation takes place at `0^(@)C`C. Because ice is solidD. Because ice cubes do not constitute isolated system |
| Answer» Correct Answer - D | |
| 161. |
The densities of graphite and diamond at 298 K are 2.25 and 3.31 g `cm^(-3)`, respectively. If the standard free energy difference `(DeltaG^(@))` is equal to 1895 J `mol^(-1)`, the pressure at which graphite will be transformed diamond at 298 K isA. `9.92xx10^(5)Pa`B. `9.92xx10^(8)Pa`C. `9.92xx10^(7)Pa`D. `9.92xx10^(6)Pa` |
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Answer» Correct Answer - B Only high pressure favours the conversion. |
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| 162. |
A gas is allowed to expand in a well insulated container against a constant external pressure of `2.5 atm` from an initial volume of `2.50 L` to a final volume of `4.50 L`. The change in internal energy `Delta U` of the gas in joules will be:A. `-500J`B. `-505J`C. `+505J`D. `1136.25 J` |
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Answer» Correct Answer - B Work done in irreversible process `W=-P_("ext")DeltaV` `=-2.5[4.5-2.5]=-5 " L atm"` `=-5xx101.3 J=-505 J` Since system is well insulated q = 0 By FLOT `DeltaE=q+w` `DeltaE=W=-505 J` |
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| 163. |
When one mole of monoatomic ideal gas at T K undergoes adiabatic change under a constant external pressure of 1 atm changes volume from 1 litre to 2 litre. The final temperature in Kelvin would beA. `(T)/(2^((2//3)))`B. `T+(2)/(3xx0.0821)`C. TD. `T-(2)/(3xx0.0821)` |
| Answer» Correct Answer - D | |
| 164. |
Work done during isothermal expansion of one mole of an ideal gas from 10 atm to 1 atm at 300 K is (Gas constant = 2)A. 938.8 calB. 1138.8 calC. 1381.8 calD. 1581.8 cal |
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Answer» Correct Answer - C `-W=+2.303 nRTlog.(P_(1))/(P_(2))` `-W=2.303xx1xx2xx300log.(10)/(1)=1381.8 cal`. |
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| 165. |
The work done during the expansion of a gas from a volume of `4dm^(3)` to `6dm^(3)` against a constant external pressure of 3 atm is (1L atm = 101.32 J)A. `+ 304 J`B. `- 304 J`C. `- 6 J`D. `-608 J` |
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Answer» Correct Answer - D `W=-pDeltaV, W=-3xx(6-4)` `W=-6xx101.32(therefore "1 L atm=101.32 J")` W=-608 J |
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| 166. |
In which case reaction is spontaneousA. `DeltaH-ve, DeltaS+ve`B. `DeltaH+ve, DeltaS-ve`C. Both (a) and (b)D. None of these |
| Answer» Correct Answer - A | |
| 167. |
Entropy change in a process where 1 litre of liquid He is poured into ice cold water isA. Finite and positiveB. Finite and negativeC. ZeroD. Infinity |
| Answer» Correct Answer - A | |
| 168. |
As `O_(2)` is cooled at 1 atm pressure, it freezes to form solid I at 54.5 K. At a lower temperature, solid I rearranges to solid II, which has different crystal structure. Thermal measurements show that for the phase transition solid I to solid II, `DeltaH=-743.1 J mol^(-1) and DeltaS=-17.0 JK^(-1) mol^(-1)`. At what temperature are solids I and II in equilibriumA. 2.06 KB. 31.5 KC. 43.7 KD. 53.4 K |
| Answer» Correct Answer - C | |
| 169. |
Which of the following is an endothermic reactionA. `2H_(2)+O_(2)rarr2H_(2)O`B. `N_(2)+O_(2)rarr2NO`C. `2NaOH+H_(2)SO_(4)rarrNa_(2)SO_(4)+2H_(2)O`D. `3O_(2)+C_(2)H_(5)OHrarr2CO_(2)+3H_(2)O` |
| Answer» Correct Answer - B | |
| 170. |
Five moles of a gas is put through a series of changes as shown graphically in a cyclic process the `A rarr B, B rarr C` and `C rarr A` respectively are A. Isochoric, Isobaric, IsothermalB. Isobaric, Isochoric, IsothermalC. Isothemal, Isobaric, IsochoricD. Isochoric, Isothermal, Isobaric |
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Answer» Correct Answer - A `A rarr B`, volume is not changing (Isochoric) `B rarr C` Isobaric `C rarr A` Temperature is constant (Isothermal). |
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| 171. |
Mark the correct statementA. For a chemical reaction to be feasible, `DeltaG` should be zeroB. Entropy is a measure of order in a systemC. For a chemical reaction to be feasible, `DeltaG` should be positiveD. The total energy of an isolated system is constant |
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Answer» Correct Answer - D Total energy of an isolated system is constant. |
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| 172. |
For a cyclic processA. W = 0B. `DeltaE = 0`C. `DeltaH ne 0`D. `DeltaE ne 0` |
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Answer» Correct Answer - B For a cyclic process dE=0 and dH=0. |
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| 173. |
Identify the intensive quantities from the followingA. EnthalpyB. TemperatureC. VolumeD. Refractive index |
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Answer» Correct Answer - B::D Those physical properties which are not based upon the mass are known as intensive properties. |
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| 174. |
In thermodynamics which one of the following is not an intensive propertyA. PressureB. DensityC. VolumeD. Temperature |
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Answer» Correct Answer - C Volume is not an intensive property. |
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| 175. |
The `DeltaH_(f)^(@)` for `CO_(2)(g), CO(g)` and `H_(2)O(g)` are - 393.5, - 110.5 and - 241.8 kJ `mol^(-1)` respectively. The standard enthalpy change (in kJ) for the reaction `CO_(2)(g)+H_(2)(g)rarrCO(g)+H_(2)O(g)` isA. 524.1B. 41.2C. `- 262.5`D. `- 41.2` |
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Answer» Correct Answer - B `DeltaH=SigmaDeltaH, "(Product)"-SigmaDeltaH`, `"(reactant)"=(-110.5-241.08)-(-393.5)=41.2 kJ mol^(-1)`. |
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| 176. |
For which change `DeltaH ne DeltaE` :A. `H_(2)+I_(2)rarr2HI`B. `HCl+NaOHrarrNaCl`C. `C_((s))+O_(2(g))rarrCO_(2(g))`D. `N_(2)+3H_(2)rarr2NH_(3)` |
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Answer» Correct Answer - D `DeltaH=DeltaE+DeltanRT` `therefore` For `DeltaH ne DeltaE. Deltan ne 0` `Deltan=0` for reaction (a) as both reactants & products have same no. of molecules `Deltan=0` for (c ) as C is in solid state. Further `DeltaH=DeltaE` for reaction (b) as it is carried out in liquid state Moreover `Deltan=0` for this reaction also, `HCl+NaOHrarrNaCl+H_(2)O`. |
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| 177. |
Standard molar enthalpy of formation of `CO_(2)` is equal toA. ZeroB. The standard molar enthalpy of combustion of gaseous carbonC. The sum of standard molar enthalpies of formation of CO and `O_(2)`D. The standard molar enthalpy of combustion of carbon (graphite) |
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Answer» Correct Answer - D Standard molar heat enthalpy `(H^(@))` of a compound is equal to its standard heat of formation from most stable states of initial components. |
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| 178. |
Assertion(A) : For the combustion reactions, the value of `DeltaH` is always negative. Reason(R ) : The combustion reactions are always endothermic.A. If both assertion and reason are true and the reason is the correct explanation of the assertion.B. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false. |
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Answer» Correct Answer - C Combustion reaction are always accompanied by the evolution of heat therefore, for such reactions the value of `DeltaH` is always negative. |
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| 179. |
The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at `0^(@)C` isA. 10.52 cal/(mol K)B. 21.04 cal/(mol K)C. 5.260 cal/(mol K)D. 0.526 cal/(mol K) |
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Answer» Correct Answer - C `DeltaS=(DeltaH)/(T)=(1.435xx10^(3))/(273)=5.260 cal//"molK"` |
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| 180. |
The average molar heat capacities of ice and water are `37.6 mol^(-1)` and `75.2 J mol^(-1)` respectively and the enthalpy of fusion of ice is 6.020 kJ `mol^(-1)`. The amount of heat required to change 10 g of ice at `-10^(@)C` to water at `10^(@)C` would beA. 2376 JB. 4752 JC. 3970 JD. 1128 J |
| Answer» Correct Answer - C | |
| 181. |
Which of these species has a standard enthalpy of formation equal to zeroA. `F_(2)(g)`B. F(g)C. HF(aq)D. `F^(-)`(aq) |
| Answer» Correct Answer - A | |
| 182. |
Which of the following is always negative for exothermic reactionA. `DeltaH`B. `DeltaS`C. `DeltaG`D. None of these |
| Answer» Correct Answer - A | |
| 183. |
Which of the following reactions is not exothermicA. `C(s)+O_(2)(g)rarrCO_(2)(g)`B. `C(s)+2S(s)rarrCS_(2)(g)`C. `CH_(4)(g)+2O_(2)(g)rarrCO_(2)(g)+2H_(2)O(l)`D. `CO(g)+(1)/(2)O_(2)(g)rarrCO_(2)(g)` |
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Answer» Correct Answer - B This reaction absorbed heat, so it is endothermic reaction. |
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| 184. |
Statement 1 : The endothermic reactions are favoured at lower temperature and the exothermic reactions are favoured at higher temperature. Statement 2 : When a system in equilibrium is disturbed by changing the temperature, it will tend to adjust itself so as to overcome the effect of change.A. Statement 1 is true, statement-2 is true, statement 2 is a correct explanation for statement 1B. Statement 1 is true, statement 2 is true, statement 2 is not a correct explanation for statement 1C. Statement 1 is true, statement 2 is falseD. Statement 1 is false, statement 2 is true |
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Answer» Correct Answer - D The statement is clearly wrong accroding to Le-chateliers principle, which states that, 'Increase in temperature shifts the equilibrium in the forward directon of those reaction which proceed with absorption of heat (endothermic reactions), and in the backward direction of those reactions which proceed with the evolution of heat (exothermic reactions),' E is clearly true again according to Le-chatelier principle. |
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| 185. |
The heat of combustion of carbon to `CO_(2)` is `-393.5` kJ/mol. The heat released upon formation of 35.2 g of `CO_(2)` from carbon and oxygen gas isA. `+315` kJB. `-31.5` kJC. `-315` kJD. `+31.5` kJ |
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Answer» Correct Answer - C `C+O_(2)rarrCO_(2)DeltaH=-393.5 kJ//mol` `because` 44gm of `CO_(2)` form by which heat released `=-393.5 kJ` `therefore` 1 gm of `CO_(2)` form by which heat released = `-(393.5)/(44)` `therefore` 35.2 gm (given) of `CO_(2)` form by which heat released `=-(393.5)/(44)xx35.2=-315 kJ`. |
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| 186. |
How many grams of ice at `0^(@)C` can be melted by the addition of 500 J of heat (The molar heat of fusion for ice is 6.02 kJ `mol^(-1)`)A. 0.0831 gB. 1.50 gC. 3.01 gD. 12.0 g |
| Answer» Correct Answer - B | |
| 187. |
Assertion : Heat of neutralization of perchloric acid, `HClO_(4)` with NaOH is same as is that of HCl and NaOH. Reason : Both HCl and `HClO_(4)` are strong acidsA. If the assertion and reason are true and the reason is the correct explanation of the assertionB. If both assertion and reason are true but reason is not the correct explanation of the assertionC. If assertion is true but reason is falseD. If the assertion and reason both are false. |
| Answer» Correct Answer - A | |
| 188. |
The heat of neutralization will be highest inA. `NH_(4)OH and CH_(3)COOH`B. `NH_(4)OH and HCl`C. `KOH and CH_(3)COOH`D. `KOH and HCl` |
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Answer» Correct Answer - D Strong base (KOH) and strong acid (HCl). |
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| 189. |
An exothermic reaction is one in which the reacting substancesA. Have more energy than the productsB. Have less energy than the productsC. Are at a higher temperature than the productD. None of the above |
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Answer» Correct Answer - A For exothermic reaction `H_(p) lt H_(R)`. For endothermic reactions `H_(p) gt H_(R)`. |
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| 190. |
2.1 g of Fe combines with S evolving 3.77 kJ. The heat of formation of FeS in kJ/mol isA. `- 1.79`B. `- 100.5`C. `- 3.77`D. None of these |
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Answer» Correct Answer - B `DeltaH//"mole of FeS"=(3.77xx56)/(2.1)=100.5` |
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| 191. |
Heat of neutralization of strong acid and weak base isA. 57.1 kJ `mol^(-1)`B. 13.7 kJ `mol^(-1)`C. Less than 13.7 kcal `mol^(-1)`D. More than 13.7 kcal `mol^(-1)` |
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Answer» Correct Answer - C Heat of neutralization of strong acid and weak base is less than 13.7 kcal `mol^(-1)`. |
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| 192. |
The enthalpy of neutralization of oxalic acid by a strong base is `-25 kcal mol^(-1)`. The enthalpy of neutralization of strong acid and strong base is `-13.7` kcal `"equiv"^(-2)`. The enthalpy of dissociation of `H_(2)C_(2)O_(4) iff 2H^(+)+C_(2)O_(4)^(2-)` isA. 1.0 kcal `mol^(-1)`B. 2.0 kcal `mol^(-1)`C. 18.55 kcal `mol^(-1)`D. 11.7 kcal `mol^(-1)` |
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Answer» Correct Answer - B `H_(2)C_(2)O_(4)iff2H^(+)+C_(2)O_(4)^(2-), DeltaH_(1)=Q` and `2H^(+)+C_(2)O_(4)^(2-)+2Na^(+)+2OH^(-)rarr2Na^(+)+C_(2)O_(4)^(2-)+2H_(2)O_((l)),DeltaH_(2)=-13.7xx2` Adding both `H_(2)C_(2)O_(4)+Na^(+)+OH^(-)" "Na^(+)+C_(2)O_(4)^(2-)+H_(2)ODeltaH_(3)=-25.4 kcal` So, `Q-13.7xx2=-25.4 kcal" " = Q=2 kcal mol^(-1)`. |
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| 193. |
Heat of neutralization of a strong acid by a strong base is a constant value becauseA. Salt formed does not hydrolyseB. Only `H^(+)` and `OH^(-)` ions react in every caseC. The strong base and strong acid react completelyD. The strong base and strong acid react in aqueous solution |
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Answer» Correct Answer - B In neutralization of a strong acid and base only `H^(+)` and `OH^(-)` ions react. |
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| 194. |
In the reaction: `H_(2)+Cl_(2)rarr2HCl, DeltaHCl, DeltaH=194 kJ`. Heat of formation of HCl isA. `+ 97` kJB. `+ 194 kJ`C. `- 194 kJ`D. `- 97 kJ` |
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Answer» Correct Answer - A Heat of formation = `(194)/(2)=97` kJ. |
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| 195. |
The heat of reaction at constant pressure is given byA. `E_(P)-E_(R)`B. `E_(R)-E_(P)`C. `H_(P)-H_(R)`D. `H_(R)-H_(P)` |
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Answer» Correct Answer - C `DeltaH(H_(P)-H_(R))=q_(p)`. |
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| 196. |
When `50 cm^(3)` of a strong acid is added to `50 cm^(3)` of an alkali, the temperature rises by `5^(@)C`. If `250cm^(3)` of each liquid are mixed, the temperature rise would beA. `5^(@)C`B. `10^(@)C`C. `25^(@)C`D. `20^(@)C` |
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Answer» Correct Answer - A No doubt heat evolved during neutralisation of `250cm^(3)` of eacch acid and base is five time the heat evolved during neutralisation of `50cm^(3)` of each acid and base but the quantity if solution taking heat is also five time and thus sam temperature rise is noticed. |
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| 197. |
When a strong acid, strong base or their salt are dissolved in water, they are completely ionized. If a strong acid is added to a strong base. `H^(+)` ions from the former combine with `OH^(-)` ions of the latter forming water. The formation of each water molecule liberates a certain quantity of energy and the reaction is exothermic. The heat liberated when one mole of water is formed by combining hydrochloric acid and sodium hydroxide is 13.7 kcal. The heat liberated when one mole of water is formed by combining sulphuric acid and sodium hydroxide isA. 25.5 kcalB. 8.5 kcalC. 13.7 kcalD. 34 kcal |
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Answer» Correct Answer - C `H^(+)+OH^(-)rarrH_(2)O, DeltaH_("neutralization")=13.7 kcal`. |
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| 198. |
`0.06` mole of `KNO_(3)` is added to `100cm^(3)` of water at `298 K`. The enthalpy of `KNO_(3)(aq)` solution is `35.8 kJ mol^(-1)`. After the solute is dissolved, the temerature of the solution will beA. 293 KB. 298 KC. 301 KD. 304 K |
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Answer» Correct Answer - A On applying `mC_(P).DeltaT`. |
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| 199. |
Heat of formation in the reaction `H_(2)+Cl_(2)rarr2HCl+44 kcal` isA. 44 kcalB. 44000 kcalC. 22 kcalD. 11 kcal |
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Answer» Correct Answer - C `DeltaH_(f)=(44)/(2)kcal=22 kcal`. |
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| 200. |
If the enthalpy of B is greater than of A, the reaction `A rarr B` isA. EndothermicB. ExothermicC. InstantaneousD. Spontaneous |
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Answer» Correct Answer - A For exothermic reactions `H_(p) lt H_(R)`. For endothermic reaction `H_(p) gt H_(R)`. |
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