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Thermodynamics · Question 32

NEET 2013 (Karnataka)MCQEasy📈 Topic in 12% papers+4−1
1

Three thermochemical equations are given below (i) C(graphite) + O2(g) CO2(g); r H = x kJ mol-1 (ii) C(graphite) + 12O2(g) CO(g); r H = y kJ mol-1 (iii) CO(g) + 12O2(g) CO2(g); r H = z kJ mol-1 Based on the above equations, find out which of the relationship given below is correct.

  1. z = x + y
  2. x = y + z
  3. y = 2z − x
  4. x = y − z

Answer

(2) x = y + z

Solution

Adding equations (ii) and (iii):

C(graphite) + O2(g) CO2(g), which is equation (i).

As per Hess's law, the enthalpy change is the same whether the reaction occurs in one step or several steps.

∴ x = y + z

Answer: (2)

NEET 2013 (Karnataka)

Keep practising — Thermodynamics

2

Equal volumes of two monoatomic gases, A and B at same temperature and pressure are mixed. The ratio of specific heats (Cp/Cv) of the mixture will be

  1. 0.83
  2. 1.50
  3. 3.3
  4. 1.67
Out of syllabusAIPMT 2012 (Mains)
3

In which of the following reactions, standard reaction entropy change ( S ) is positive and standard Gibb's energy change ( G ) decreases sharply with increasing temperature ?

  1. C(graphite)+ 12O2(g) CO(g)
  2. CO(g)+ 12O2(g) CO2(g)
  3. Mg(s)+ 12O2(g) MgO(s)
  4. 12C(graphite)+ 12O2(g) 12CO2(g)
AIPMT 2012 (Prelims)
4

The enthalpy of fusion of water is 1.435 kcal/mol. The molar entropy change for the melting of ice at 0 C is

  1. 10.52 cal/(mol K)
  2. 21.04 cal/(mol K)
  3. 5.260 cal/(mol K)
  4. 0.526 cal/(mol K)
AIPMT 2012 (Prelims)
5

Standard enthalpy of vaporisation vapH for water at 100 C is 40.66 kJ mol-1. The internal energy of vaporisation of water at 100 C (in kJ mol-1) is

  1. +37.56
  2. -43.76
  3. +43.76
  4. +40.66
AIPMT 2012 (Prelims)
6

Consider the following processes : array|l|c| & H (kJ/mol) \ 12A B & +150 \ 3B 2C + D & -125 \ E + A 2D & +350 \ array For B + D E + 2C, H will be

  1. 525 kJ/mol
  2. -175 kJ/mol
  3. -325 kJ/mol
  4. 325 kJ/mol
AIPMT 2011 (Mains)
7

If the enthalpy change for the transition of liquid water to steam is 30 kJ mol-1 at 27 , the entropy change for the process would be

  1. 10 J mol-1 K-1
  2. 1.0 J mol-1 K-1
  3. 0.1 J mol-1 K-1
  4. 100 J mol-1 K-1
AIPMT 2011 (Prelims)
8

Enthalpy change for the reaction, 4H(g) 2H2(g) is -869.6 kJ The dissociation energy of H-H bond is

  1. -434.8 kJ
  2. -869.6 kJ
  3. +434.8 kJ
  4. +217.4 kJ
AIPMT 2011 (Prelims)
9

Which of the following is correct option for free expansion of an ideal gas under adiabatic condition ?

  1. q = 0, T 0, w = 0
  2. q 0, T = 0, w = 0
  3. q = 0, T = 0, w = 0
  4. q = 0, T < 0, w 0
AIPMT 2011 (Prelims)
10

Match List I (Equations) with List II (Type of processes) and select the correct option.

  1. A - (i), B - (ii), C - (iii), D - (iv)
  2. A - (iii), B - (iv), C - (ii), D - (i)
  3. A - (iv), B - (i), C - (ii), D - (iii)
  4. A - (ii), B - (i), C - (iv), D - (iii)
AIPMT 2010 (Mains)
11

Three moles of an ideal gas expanded spontaneously into vacuum. The work done will be

  1. infinite
  2. 3 Joules
  3. 9 Joules
  4. zero
AIPMT 2010 (Mains)

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