MOCK TEST FOR NDA, ENGINEERING ENTRANCE EXAMINATION
1.CHEMISTRY
QUESTION NO.1
For N2(g) + 3H2(g) ⇌ 2NH 3(g), 
H is equal to
H is equal to
E + 2RT
E - 2RT
E + RT
E - RTANSWER
We know that
H = 
E + 
nRTIn the present case
n = - 2
H = 
E - 2RTQUESTION 2
Which of the following pairs has the highest heat of neutralisation?
NH4OH and CH3COOH
NH4OH and HCl
KOH and CH3COOH
KOH and HCl
ANSWER
Since both acid and base are strong in this case. So heat of neutralization is highest in this case.
QUESTION 3
Directions: In the following question, a statement of Assertion is given; followed by a corresponding statement of Reason just below it. Of the statement mark the correct answer as:
(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 the reason is not the correct explanation of the assertion.
(c) If assertion is true statement, but reason is false.
(d) If both assertion and reason are false.
Assertion: Molar entropy of vaporisation of water is different from ethanol.
Reason: Water is more polar than ethanol.
(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 the reason is not the correct explanation of the assertion.
(c) If assertion is true statement, but reason is false.
(d) If both assertion and reason are false.
Assertion: Molar entropy of vaporisation of water is different from ethanol.
Reason: Water is more polar than ethanol.
(a)
(b)
(c)
(d)
ANSWER
Molar entropy of vaporisation of water is different from ethanol. Molar entropy is independent of polarity of the molecule.
QUESTION 4
Standard enthalpies of formations of CO2 (g), CO (g), N2O (g) and NO2(g) in kJ/mol are - 393, - 110, 81 and 34 respectively. The  value in kJ of the reaction 2NO2 (g) + 3CO (g)  N2O (g) + 3CO2 (g) is |
– 836
– 1460
1460
836
ANSWER
By using the formula:
D H for the reaction = [sum of heat of formation for products] - [sum of heat of formation for reactants]
The value comes out to be – 836 KJ
D H for the reaction = [sum of heat of formation for products] - [sum of heat of formation for reactants]
The value comes out to be – 836 KJ
QUESTION 5
In which of the following processes, maximum increase in entropy is observed?
Melting of ice
Sublimation of naphthalene
Condensation of water
Dissolution of salt in water
ANSWER
Entropy of gaseous phase is maximum. So sublimation of naphthalene will involve maximum entropy increase.
QUESTION 6
| Directions: The following question has four choices out of which ONLY ONE is correct. The enthalpy of neutralization of HCN by NaOH is - 12kJ/mol. The enthalpy of ionization of HCN is |
- 12 KJ/ mol
69 KJ/ mol
12 KJ/ mol
- 45 KJ/ mol
ANSWER
The enthalpy of ionization of HCN is reverse of the enthalpy of neutralization of HCN. So enthalpy of ionization of HCN is 12 kJ/mol.
QUESTION 7
Directions: The following question has four choices out of which ONLY ONE is correct.
Dissolution of ammonium chloride in water is an endothermic change. At constant temperature it is accompanied by
Dissolution of ammonium chloride in water is an endothermic change. At constant temperature it is accompanied by
no change in enthalpy
decrease in entropy
no change in entropy
increase in entropy
ANSWER
Entropy in liquid state is more than that in solid state. So dissolution of ammonium chloride in water is accompanied by increase in entropy.
QUESTION 8
| The enthalpy of formation for C2H4(g), CO2(g) and H2O(l) at 250C and 1 atm pressure is 52, – 394, – 286 kJ mol−1 respectively. The enthalpy of combustion of C2H4(g) will be |
− 141.2 kJ mol−1
− 1412 kJ mol−1
+ 141.2 kJ mol−1
+ 1412 kJ mol−1
ANSWER
C2H4 + 3O2 → 2CO2 + 2H2O
= −1412 kJ
QUESTION 9
| Directions: The following question has four choices out of which ONLY ONE is correct. For the reaction 2H2 + O2  2H2O,  H = - 571 kJ. Bond energy of H - H = 435 kJ/mol, O - O = 498 kJ/mo. Calculate the average bond energy (in kJ/mol) of O - H bond using this data. |
484
- 484
271
- 271
ANSWER
Using the formula:
H = Energy of Bonds Broken - Energy of Bonds formed
The average bond energy (in kJ/mol) of O - H bond comes out to be 484.
H = Energy of Bonds Broken - Energy of Bonds formedThe average bond energy (in kJ/mol) of O - H bond comes out to be 484.
QUESTION 10
| The work done during the expansion of a gas from a volume of 4 dm3 to 6 dm3 against a constant external pressure of 3 atm is |
- 6 J
- 608 J
+ 304 J
- 304 J
ANSWER
Expansion work w is given by following equation:
W = P
V
= 3 atm (6 - 4 dm3)
= 3 atm (2 dm3)
= 6 L atm.
= 101.32
6 = 607.92 J
Since work is done by the system hence - 607.92 J
W = P
V= 3 atm (6 - 4 dm3)
= 3 atm (2 dm3)
= 6 L atm.
= 101.32
6 = 607.92 JSince work is done by the system hence - 607.92 J
PHYSICS MATHS QUESTIONS WILL PUBLISHED WITHIN 1 HOUR.
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