This section includes 7 InterviewSolutions, each offering curated multiple-choice questions to sharpen your Current Affairs knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Heat of neutralisation of CH_3COOH_((aq)) with NaOH_((aq)) is - 55.2kJ. What is heat of ionisation of CH_3COOH ? |
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Answer» |
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| 2. |
Heat of neutralisation of a strong acid is ____ than that of a weak acid. |
| Answer» SOLUTION :`DeltaH_("ionisation")^(sigma)=+"42.77 KJ MOL"^(-1)`. | |
| 3. |
Heat of neutralisation of a weak acid HA by NaOH is -"12.13 kJ mol"^(-1). Calculate the enthalpy of ionization of HA. |
| Answer» SOLUTION :`DeltaH_("ionisation")^(SIGMA)=+"42.77 kJ mol"^(-1)`. | |
| 4. |
Heat of neutralisation of a polybasic acid by strong base is -54.8 kcal mol^(-1). What is basicity of the acid? |
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Answer» |
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| 5. |
Heat of neutralisation for the reaction NaOH + HCl rarr NaCl + H_(2)O " is " -57.1 kJ "mole"^(-1). The heat relased when 0.25 moles of NaOH is treated with 0.25 moles of HCl is |
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Answer» 22.5 K.J/mole |
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| 6. |
Heat of Hydration of Na^(+) (size 102 Pm) = - 397J Kj mol^(-1) whereas Ca^(2+) (size 100 Pm) = - 1650 kJ mol^(-1). Explain the difference. |
| Answer» Solution :`Ca^(2+)` is smaller in size then `Na^(+)` and ALSO it has HIGHER charge therefore, its HYDRATION ENERGY is more than that of `Na^(+)` | |
| 7. |
Heat of formation of water and heats of combustion of ethylene and acetylene are respectively 286, -1410 and -1299 kJ mol^(-1), Calculate the heat of the reaction, C_2H_(2(g)) + H_(2(g)) to C_(2)H_(4(g)). |
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Answer» |
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| 8. |
The reaction which shows standard heat of formation of water correctly is |
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Answer» `-251.9KJ` |
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| 9. |
Heat of formation of CO and CO_2 are -26.4, -94.0 kcal/mole respectively. What is the heat of combustion of CO in kcals? |
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Answer» `+26.4` |
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| 10. |
Heat of formation of 2 moles of NH_(3)(g) " is" -90 kJl bond energies of H-H and N-H bonds are 435 kJ and 390 kJ mol^(-1) respectively. The value of the bond energy of N -= N is (1000- (x^(2) + x +25)) kJ/mol What is x ? |
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Answer» So, `(1)/(2) N_(2(G)) + (3)/(2) H_(2(g)) rarr NH_(2(g)), Delta H = - 45kJ` So, `-45 = (3)/(2) (H - H) + (1)/(2) (N -= N) - 3 (N - H)` `(3)/(2) (435) + (1)/(2) (N -= N) - 3(390)` `N -= N = 945` From the given CONDITION `945 = 1000 - (x^(2) + x + 25)` So, `x^(2) - x + 25= 55`, On solving x = 6S |
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| 11. |
Heat of dissociationof aceticacidis 0.30 kcalmol^(-1) . Hence,enthalpy change when 1 molofCa(OH)_(2) is completelyneutralized by aceticacid would be |
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Answer» `-13.4 kcal` 2 moles of `OH^(-)` ions require 2 moles of `H^(+)` ions for complete neutralization. Heat of dissociation of acetic acidto produce 2 moles of`H^(+)` ions `= 2 xx 0.30 kcal = 0.6 kcal`. Hence, net heat produced `=27.4 - 0.6 =26.8 kcal, i.e., DeltaH =- 26.8 kcal` |
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| 12. |
Heat of combustion of methane is ……….. KJ/ mol . |
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Answer» `-87.78` |
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| 13. |
Heat of combustion of carbon is -96 k, cals. When some quantity of carbon is burnt in oxygen, 48 k.cals of heat is liberated. What is the volume (in lits) of O_2 at STP reacted with this carbon |
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Answer» 48 |
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| 14. |
Heat of combustion of C_(2)H_(4) is -337 kCal. If 5.6 lit O_(2) is used at STP, in the combustion heat liberated is _____ kCal |
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Answer» 28.08 |
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| 15. |
Heat of combustion of benzoic acid (C_6H_5COOH) at constant volume at 25^@C is -3233KJ//"mole". When 0.5g of benzoic acid is burnt in bomb calorimeter, the temperature of calorimeter increased by 0.53^@C. Now in the same bomb calorimeter 1g of C_2H_6 burnt then temperature increased by 2.04^@C. DeltaHfor combustion of C_2H_6is |
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Answer» `-1530KJ//"MOLE"` |
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| 16. |
Heat of combustion of A(s) is -10 k"cal" mol^(-1) and that of B(s) is -15 Kcal mol^(-1). Mixture containing 3 moles A(s) and x moles B(s) on combustion released 105 kcal of heat. What is the value of x? |
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Answer» `B + O_(2) rarr Delta H_(2) = -15` Kcal `3A xx xB = 10^(5)` `rArr 3(10) + x (15) = 10^(5) rARr x = 5` |
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| 17. |
Heats of combustion of benzene, carbon and hydrogen are - 782, -94, -68 kcal mol^(-1) respectively. Calculate heat of formation of benzene. |
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Answer» Solution :`C_(6)H_((s))+O_(2)(g)to 6CO_(2)(g)+3H_(2)O_((l)),DeltaH_(1)=-782k.cal` `C_((s))+O_(2)(g)to CO_(2)(g),DeltaH_(2)=-94Kcal` `H_(2)(g)+1/2O_(2)(g)to H_(2)O_((l)),DELTAH=-68Kcal ` The required EQUATION is `6C_((s))+3H_(2)(g)to C_(6)H_(6)(l),DeltaH=?` Heat of formation of benzene =`DeltaH=-DeltaH_(1)+6DeltaH_(2)+3DeltaH_(2)=+14Kcal`. |
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| 18. |
Heat of combustion is always |
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Answer» positive |
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| 19. |
Heat of combustion is always ………….. . |
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Answer» POSITIVE |
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| 20. |
Heat of combustion is always ____ |
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Answer» POSITIVE |
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| 21. |
Heats of atmoisation of ozone and oxygen are 25 units and 30 units respectively. What is the heat of ozonisation of one mole of oxygen is the same units? |
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Answer» `O_(2) rarr 20, Delta H_(2) = 30` `O_(2) rarr (2)/(3) O_(3), Delta H` `Delta H = +30 - (2)/(3) xx 25 = (15)/(3) = 5` |
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| 22. |
Heat liberated when 100 ml of 1N NaOH is neutralized by 300 ml of 1N HCl ____ |
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Answer» SOLUTION :BASE =`V_1`= 100 ml `N_1=1N` Acid = `N_2`=300 ml `N_2`=1N Enthalpy of neutralization of 1000 ml =57.3 KJ `therefore` Enthalpy of neutralization of 100 ml =`(57.3 kJ)/1000xx100`= 5.73 kJ |
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| 23. |
Heat liberated in the neutralisation of 500 ml of 1N HCl and 500ml of 1N NH_(4)OH is -1.36 K.Cals. The heat of ionisation of NH_(4)OH is |
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Answer» `10.98`K.Cals |
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| 24. |
Heat is considered as a path function, but in an endothermic process , the heat absorbed by the system undercertain specific conditions is independent of path. What are those conditions ? |
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Answer» Solution :Heat BECOME INDEPENDENT of the path , at constant volume and constant pressure. (i) At constant Volume : By I law of THERMODYNAMICS, `DeltaU=Q+w` or `q = DeltaU-W`. Sine `W=-PDeltaV` therefore , `q=DeltaU+PDeltaV` . But as volume remains constant, `DeltaV=0` `:.qv=DeltaU` Since `DeltaU` is a state FUNCTION , therefore qv is also state function. (ii) At constant pressure : `qp=DeltaU+PDeltaV` But `DeltaM=DeltaU+PDeltaV` `DeltaU=DeltaH-PDeltaV` `q_(p)=DeltaH-PcancelDeltaV+PcancelDeltaV` `:'qv=DeltaU` since `DeltaH` is a state function , therefore `q_(p)` is a state function. |
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| 25. |
Heat has randomisin influence on a system and temperature is the measure of average chaotic motion of particles in the system . Write the mathematical relation which relates these three parameters. |
| Answer» SOLUTION : `DELTAS =( Q"REV")/( T)` | |
| 26. |
Heat has randomising influence on a system and temperature is the measure of average chaotic motion of particles in the system. Write the mathematical relation which relates these three parameters. |
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Answer» Solution :Heat has randomising influence on a system and TEMPERATURE is the measure of average chaotic motion of particles in the system. The mathematical relation which relates these three PARAMETERS is `Delta S = (q_("rev") )/( T)` Here, `Delta S= ` Change in ENTROPY `q_("rev") =` Heat of reversible REACTION T = Temperature |
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| 27. |
Heat capacity (C_(p)) is an extensive property but specific heat (c) is intensive property. What will be the relation between C_(p) " and " c for 1 mole of water ? |
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Answer» Solution :For water, molar heat CAPACITY, `C_(P) = 18 xx` SPECIFIC heat, C `C_(P) = 18 xx c` Specific heat `c = 4.18 Jg^(-1) K^(-1)` Heat capacity, `C_(P) = 18 xx 4.18 JK^(-1) MOL^(-1)` `= 753 JK^(-1) mol^(-1)` |
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| 28. |
Molar heat capacity (C_(p)) of water of constant pressure is 75JK^(-1) mol^(-4). The increase in temperature (in K)of 100g of water when I kJof heat is supplied to it is |
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Answer» `1.8 xx 10^(-3) MOL` |
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| 30. |
Heat capacity (C_(p)) in an extensive propertybut specificheat (c )is an intensive property . What will be the relationbetween C_(p)and c for 1 mol of water ? |
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Answer» Solution :For water, molarheat CAPACITY `(C_(p)) = 18 xx `specific heat `:.C_(p)= 18 xx c` But specificheat of water , `c=4.18 J G^(-1) K^(-1)` `:. `HEATCAPACITY , `C_(p) =18 xx 4.18 JK^(-1) MOL^(-1) = 75.3 JK^(-1) mol^(-1)` |
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| 31. |
Heat capacity (C_p) is an extensive property but specific heat (c) is an intensive property. What will be the relation between C_p and c for 1 mol of water? |
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Answer» Solution :Molar heat capacity for water, `C_p= 18 XX` SPECIFIC heat, c `C_p= 18 xx` Specific heat `c= 4.18 "J" g^(-1) "K"^(-1)` (for water) Heat capacity, `C_(p) = 18 xx 4.18 "JK"^(-1) "MOL"^(-1)` `= 753 "JK"^(-1) "mol"^(-1)` |
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| 32. |
Temperature of 1 mole of an ideal gas is increased from 300 K to 310 K under isochoric process. Heat supplied to the gas in this process is Q = 25 R, where R = universal gas constant. What amount of work has to be done by the gas if temperature of the gas decreases from 310 K to 300 K adiabatically? |
| Answer» ANSWER :D | |
| 33. |
Heat balance on earth surface is maintained by circulation of air in |
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Answer» TROPOSPHERE |
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| 34. |
He_2 cannot exist as stable molecule. Justify this statement on the basis of bond order. |
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Answer» Solution :The electronic configuration of `He_2` is `sigma_(1s)^2 sigma^*_1s^2` BOND order = `1/2(N_b-N_a)` = 1/2(2-2) = 0, hence cannot EXIST |
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| 35. |
He_(2) does not exist. Explain in terms of LCAO. |
| Answer» SOLUTION :the COMBINING CAPACITY is ZERO | |
| 36. |
The size of a microscopic particle is 1 micron and its mass is 6 xx 10^(-13)g. If its position may be measured to within 0.1% of its size, the uncertainity in velocity (in cm^(-1)) is approximately |
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Answer» `(10^(-7))/(4PI)` `Delta V = h/(4pim) xx1/(Deltax) = (10^(-7))/(4pi)` |
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| 37. |
The ratio of the wavelength of the last line of Balmer series and the last line of Lyman series is : |
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Answer» `2.5 :1` n=2 for `16(ST)` line , n = 3 for `2^(nd)` line n = 4 for `3^(rd)` line , on SOLVING ratio is `2.5:1` |
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| 38. |
he product obtained as a result of a reaction of nitrogen with CaC_2 is ........ |
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Answer» `CA(CN)_3` `CaC_2 +N_2 overset(300- 350^@ C)to UNDERSET("Calcium cyanide")(Ca(CN)_2)` |
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| 39. |
Order of intemolecular attractive forces |
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Answer» WATER `LT` ALCOHOL `lt` Ether |
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| 40. |
he figure indicates the energy level diagram of an atom and the origin of six spectral lines in emission (e.g. line no. 5 arises from the transition from level B to A). Which of the following spectral lines will also occur in the absorption spectrum ? |
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Answer» 4,5,6 |
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| 41. |
He atom can be excited to 1s^(1) 2p^(1) by lambda=58.44nm. If lowest excited state for He lies 4857cm^(-1) below the above. Calculate the energy for the lower excitation state. |
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Answer» |
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| 42. |
HCOOH reacts with conc. H_(2)SO_(4) to produce |
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Answer» CO |
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| 43. |
HCOOH reacts with conc. H_(2)SO_(4) to give : |
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Answer» `CO_(2)` |
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| 44. |
HCN_((aq))+NaOH_((aq))to NaCN_((aq)) + H_(2)O_((1)), Delta H=-12.13 KJ Calculate heat of ionisation of HCN . |
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Answer» Solution :`H_((aq))^(+)+OH_((aq))^(-) to H_(2)O_((1)),DeltaH=-57.3KJ` ……(1) `HCN_((aq))+OH_((aq))^(-)to H_(2)O_((1))`,…….(2) EQUATION (2) -equation (1) GIVES, `HCN_((aq))to H_((aq))^(-) + CN_((aq))^(-),Delta H=+45.17KJ` HeatOf ionisation of `HCN=+45.17KJmol^(-1)`. |
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| 45. |
HCN_((aq)) + NaOH_((aq)) to NaCN_((aq)) + H_2O_((l)) , DetlaH = -12.13 kJ. Calculate heat of ionisation of HCN. |
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Answer» SOLUTION :`H_((aq))^(+) + OH_((aq))^(-) to H_2O_((l)) , Delta H = -57.3 KJ` ……(1) `HCN_((aq)) + OH_((aq))^(-) to H_2O_((l)) + CN_((aq))^(-)`, `DELTAH = -12.13 kJ`.....(2) Equation (2) – equation (1) gives , `HCN_((aq0) to H_((aq))^(-) + CN_((aq))^(-) , DeltaH = +45.17 kJ` Heat of ionisation of `HCN = +45.17 kJ mol^(-1)`. |
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| 46. |
HCN _((aq)) + NaOH _((aq)) to NaCN _((aq)) + H _(2) O_((l)) , Delta H =-12.13 KJ.Calculate heat of ionisation of HCN. |
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Answer» SOLUTION :`H _((aq)) ^(+) + OH _((aq) ) ^(-) to H _(2) O _((l)) ,DELTA H =-57.3KJ…..(1)` `HCN_((aq)) + OH _((aq))^(+) to H _(2) O _((l )) + CN _((aq)), ^(-),Delta H =-12.13 KJ…..(2)` Equation (2) - equation (1) GIVES, `HCN _((aq)) to H _((aq)) ^(-) + CN _((aq)) ^(-) , Delta H = + 45.17KJ` Heat of ionisation of `HCN = + 45.17kJ mol ^(-1).` |
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| 47. |
HClO_4 is a poor conductor in |
| Answer» Solution :In acetic acid it is a weakelectrolyte | |
| 48. |
HCl is produced in the stomach which can be neutralised by Mg(OH)_2 in the form of milk of magnesia. How much Mg(OH)_2 is required to neutralise one mole of stomach acid? |
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Answer» 29.16 g No. of moles of `Mg(OH)_2` REQUIRED for 2 moles of HCL = 1 No. of moles of `Mg(OH)_2` required for 1 mole of HCl = 0.5 MASS of 0.5 mol of `Mg(OH)_2=58.33xx0.5=29.16g` |
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| 49. |
_______HCl is bad conductor of electricity but _______ HCl is good conductor |
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Answer» Soild, AQUEOUS |
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| 50. |
HCl gas is covalent and NaCl is an ionic compound. This is because |
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Answer» sodium is highly electropositive |
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