NEET Chemistry Thermodynamics MCQs Set A

Question: Tea placed in thermos flask is an example of

• a) Open system
• b) Close system
• c) Isolated system
• d) It can't act as system

Answer: Isolated system

Question:  Gaseous system is placed with pressure P₁, volume V₁ and temperature T₁ , it has undergone thermodynamic changes where temperature is remaining constant, it is

• a) Adiabatic process
• b) Isothermal process
• c) Isobaric process
• d) Isochoric process

Answer: Isothermal process

Question: The respective examples of extensive and intensive properties are

• a) Enthalpy, Entropy
• b) Entropy, Enthalpy
• c) Entropy, Temperature
• d) Temperature, Entropy

Answer: Entropy, Temperature

Question: A thermally isolated, gaseous system can exchange energy with the surroundings. The mode of energy may be

• a) Heat
• b) Work
• c) Heat and radiation
• d) Internal energy

Answer: Work

Question: Which of the following is a state function?

• a) q
• b) w
• c) q + w
• d) All of these

Answer: q + w

Question:  For the reaction 

• a) ΔH = ΔE
• b) ΔH >ΔE
• c) ΔH < ΔE
• d) Can’t predicted

Answer:  ΔH >ΔE

Question: If ‘r’ is the work done on the system and ‘s’ is heat evolved by the system then,

• a) ΔE = r + s 
• b) ΔE = r – s 
• c) ΔE = r 
• d) ΔE = s

Answer:  ΔE = r – s 

Question:  For the reaction,

 Then

• a) ΔH – ΔE = (b – d) RT
• b) ΔH – ΔE = (c – b) RT
• c) ΔH – ΔE = (a + b) – (c + d) RT
• d) ΔH –ΔE = (a – d) RT

Answer:  ΔH – ΔE = (c – b) RT

Question: A system absorbs 10 kJ of heat and does 4 kJ of work. The internal energy of the system

• a) Decreases by 6 kJ
• b) Increases by 6 kJ
• c) Decreases by 14 kJ
• d) Increases by 14 kJ

Answer: Increases by 6 kJ

Question: In a reaction, all reactant and products are liquid, then

• a) ΔH > ΔE
• b) ΔH < ΔE
• c) ΔH = ΔE
• d) Can't predicted

Answer:  ΔH = ΔE

Question: Regarding the internal energy of the molecule, which of the following statement is correct?

• a) Its absolute value can be successfully calculated
• b) Its absolute value cannot be determined
• c) It is the sum of vibrational and rotational energies
• d) Both (1) & (3)

Answer: Its absolute value cannot be determined

Question:  Consider the following reaction :

What is the heat of transition of graphite into diamond?

• a) x₁+ x₂ 
• b) x₂– x₁
• c) x₁– x₂ 
• d) x₁x₂

Answer:  x₂– x₁

Question:   For the given reactions,  Steps involved are

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: The heats of combustion of yellow P and red P are –9.91kJ and –8.78kJ respectively. The heat of transition of yellow to red phosphorus is

• a) –18.69 kJ
• b) +1.13 kJ
• c) +18.69 kJ
• d) –1.13 kJ

Answer: –1.13 kJ

Question:  If the heat of formation of NO₂ is ‘x’

• a) 2x + z = y
• b) 2y + z = x
• c) 2x – z = y
• d) 2z + x = y

Answer: 2x – z = y

Question:  In the reactions

• a) x = y
• b) x = 2y
• c)

  

• d)

  

Answer:

Question:   ΔH_fC₂H₄= 12.5 kcal  

Heat of atomisation of C = 171 kcal

Bond energy of H₂= 104.3 kcal

Bond energy C – H = 99.3 kcal

What is C = C bond energy?

• a) 140.7 kcal
• b) 49 kcal
• c) 40 kcal
• d) 76 kcal

Answer: 140.7 kcal

Question:  The difference between ΔH and ΔE for the reaction

2C₆H₆(l) +15O₂(g) → 12CO2(g) + 6H₂O (l) at 25°C in kJ is

• a) –7.43 kJ
• b) +3.72 kJ
• c) –3.72 kJ
• d) +7.43 kJ

Answer: –7.43 kJ

Question:

The above data can predict that

• a) Rhombic sulphur is yellow in colour
• b) Monoclinic sulphur has metallic lustre
• c) Monoclinic sulphur is more stable
• d) ΔH_(Transition) of S(R) to S(M) is endothermic process

Answer:   ΔH_(Transition)of S(R) to S(M) is endothermic process

Question:

then the enthalpy of formation of H₂SO₄ at 298 K is

• a) –814.4 kJ
• b) –650.3 kJ
• c) –320.5 kJ
• d) –433.5 kJ

Answer: –814.4 kJ

Question:   The volume of a gas expands by 0.25 m³ at a constant pressure of 10³N m^–2. The work done is equal to

• a) 2.5 erg
• b) 250 J
• c) 250 watt
• d) 250 newton

Answer: 250 J

Question:  When 1 g of anhydrous oxalic acid is burnt at 25°C, the amount of heat liberated is 2.835 kJ. ΔH combustion is (oxalic acid : C₂H₂O₄)

• a) –255.15 kJ
• b) –445.65 kJ
• c) –295.24 kJ
• d) –155.16 kJ

Answer: –255.15 kJ

Question:  The heat of neutralization of LiOH and HCl at 25°C is 34.868 kJ mol^–1. The heat of ionisation of LiOH will be

• a) 44.674 kJ
• b) 22.232 kJ
• c) 32.684 kJ
• d) 96.464 kJ

Answer: 22.232 kJ

Question:  Which compound will absorb the maximum amount of heat when dissolved in the same amount of water?(Integral heats of solution at 25°C in kcal/mol of each solute are given in brackets)

• a) HCl (ΔH = –17.74) 
• b) HNO₃(ΔH = –7.85)
• c) NH₄NO₃(ΔH = +16.08) 
• d) NaCl (ΔH = +1.02)

Answer:  NH₄NO₃(ΔH = +16.08) 

Question:

The enthalpy of dissociation of HA is

• a) (q₁+ q₂)
• b) (q₁– q₂)
• c) (q₂– q₁)
• d) –(q₁+ q₂)

Answer:  (q₂– q₁)

Question: An athlete takes 100 g of glucose of energy equivalent to 1560 kJ. How much amount of energy is uptaken by 1 g molecule of glucose?

• a) 15.6 kJ
• b) 2808 kJ
• c) 1560 kJ
• d) 28.08 kJ

Answer: 2808 kJ

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:  For strong acid strong base neutralisation energy for 1 mole H₂O formation is –57.1 kJ. If 0.25 mole of strong monoprotic acid is reacted with 0.5 mole of strong base then enthalpy of neutralisation is

• a) –(0.25 × 57.1)
• b) 0.5 × 57.1
• c) 57.1
• d) –(0.5 × 57.1)

Answer: –(0.25 × 57.1)

Question:  The heat of combustion of solid benzoic acid at constant volume is –321.3 kJ at 27°C. The heat of combustion at constant pressure is

• a) –321.3 – 300R
• b) –321.30 + 300R
• c) –321.3 – 150R
• d) –321.3 + 900R

Answer: –321.3 – 150R

Question:

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: A cylinder contains either ethylene or propylene. 12 ml of gas required 54 ml of oxygen for complete combustion. The gas is

• a) Ethylene
• b) Propylene
• c) 1 : 1 mixture of two gases
• d) 1 : 2 mixture

Answer: Propylene

Question: The specific heat of a gas is found to be 0.075 calories at constant volume and its formula wt is 40. The atomicity of the gas would be

• a) One
• b) Two
• c) Three
• d) Four

Answer: One

Question:

for this reaction is

• a) Heat of formation of O – H 
• b) Bond energy of O – H
• c) Heat of combustion of H₂
• d) Zero at all temperatures

Answer:  Bond energy of O – H

Question:  Energy required to dissociate 4 g of gaseous H₂ into free gaseous atoms is 872 kJ at 25°C. The bond energy of H-H bond will be

• a) 8.72 kJ
• b) 4.36 kJ
• c) 436 kJ
• d) 43.6 kJ

Answer: 436 kJ

Question:  The dissociation energy of CH₄(g) is 360 kcal mol^–1 and that of C₂H₆(g) is 620 kcal mol^–1. The C – C bond energy

• a) 260 kcal mol^–1 
• b) 180 kcal mol^–1
• c) 130 kcal mol^–1
• d) 80 kcal mol^–1

Answer:  80 kcal mol^–1

Question:  The enthalpy of reaction,

2HC≡CH + 5O₂→ 4CO₂+ 2H₂O

If the bond energies of C–H, C≡C, O=O, C=O and O–H bonds are p, q, r, s, t respectively

• a) [8s + 4t] – [4p + q + 5r]
• b) [4p + 2q + 5r] – [8s + 4t]
• c) [4p + 2q + 5r + 8s + 4t]
• d) [2p + q + 5r] – [8s + 4t]

Answer: [4p + 2q + 5r] – [8s + 4t]

Question:   Using bond energy data, calculate heat of formation of isoprene

Given C–H, H–H, C–C, C = C and C(s) → C(g) respectively as 98.8 kcal, 104 kcal, 83 kcal, 147 kcal, 171 kcal

• a) – 21 kcal
• b) 21 kcal
• c) 40 kcal
• d) 50 kcal

Answer: 21 kcal

Question:   In a flask colourless N₂O₄ is in equilibrium with brown coloured NO₂. At equilibrium when the flask is heated at 100°, the brown colour deepens and on cooling it becomes less coloured. The change in enthalpy, ΔH for formation of NO₂ is

• a) Negative
• b) Positive
• c) Zero
• d) Undefined

Answer: Positive

Question:  For which of these reactions will there be ΔS positive?

• a) H₂O(g) →H₂O(l)
• b) H₂(g) + I₂(g) →2HI(g)
• c) CaCO₃(s)→ CaO(s) + CO₂(g) 
• d) N₂(g) + 3H₂(g)→2NH₃(g)

Answer:  CaCO₃(s)→ CaO(s) + CO₂(g) 

Question: For stretched rubber, Entropy

• a) Increases
• b) First increases then decreases
• c) Decreases
• d) First decreases then increases

Answer: Decreases

Question:  The least random state of H₂O is

• a) Ice
• b) Liquid water
• c) Steam
• d) Randomness is same in all

Answer: Ice

Question:  ΔS for the reaction: MgCO₃(s) → MgO(s) + CO₂(g)

• a) Zero
• b) –ve
• c) +ve
• d) ∞

Answer: +ve

Question:   The standard entropies of N₂(g), H₂(g) and NH₃(g) are 191.5, 130.5, 192.6 JK^–1 mol^–1. The value of ΔSº of formation of ammonia is

• a) –98.9 JK^–1 mol^–1
• b) Zero
• c) +129.4 JK^–1 mol–1
• d) –29.4 JK^–1 mol^–1

Answer:  –98.9 JK^–1 mol^–1

Question:   What is the increase in entropy when 11.2 L of O₂ are mixed with 11.2 L of H₂ at STP?

• a) 0.576 J/K
• b) 5.76 J/K
• c) 7.56 J/K
• d) 2.76 J/K

Answer: 5.76 J/K

Question:

• a) +25 J
• b) –125 J
• c) 135 J
• d) 315 J

Answer: –125 J

Question:  For the melting of NaCl heat required is 7.26 kcal mol^–1 and ΔS increases by 6.73 cal mol^–1k^–1. The melting point of the salt is

• a) 805.75°C 
• b) 500 K
• c) 1.77 K
• d) 1.77°C

Answer:  805.75°C 

Question:   The ΔS for the reaction

• a) –318.4JK^–1mol^–1
• b) 318.4JK^–1mol^–1 
• c) 31.84 JK^–1mol^–1
• d) 3.184 JK^–1mol^–1

Answer:  –318.4JK^–1mol^–1

Question: Which of the following is correct?

• a) 

  ΔH  ΔS    Nature of reaction

  (–) (+)   Spontaneous only at high temperature 

• b)

  ΔH  ΔS   Nature of reaction

  (+) (–)   Nonspontaneous regardless of temperature

• c)

  ΔH  ΔS   Nature of reaction

  (+) (+)  Spontaneous only at low temperature

• d)

  ΔH  ΔS    Nature of reaction

  (–) (–)    Spontaneous at all temperatures

Answer:

ΔH  ΔS   Nature of reaction

(+) (–)   Nonspontaneous regardless of temperature

Question:   Entropy of vaporisation of water at 100°C, if molar heat of vaporisation is 9710 cal mol^–1 will be

• a) 20 cal mol^–1 K^–1 
• b) 26.0 cal mol^–1 K^–1
• c) 24 cal mol^–1 K^–1
• d) 28.0 cal mol^–1 K^–1

Answer:  26.0 cal mol^–1 K^–1

Question:  A particular reaction at 27°C for which ΔH > 0 and ΔS > 0 is found to be non-spontaneous. The reaction may proceed spontaneously if

• a) The temperature is decreased
• b) The temperature is increased
• c) The temperature is kept constant
• d) It is carried in open vessel at 27°C

Answer: The temperature is increased

Question: It is impossible for a reaction to take place if

• a) ΔH is +ve and ΔS is +ve
• b) ΔH is –ve and ΔS is +ve
• c) ΔH is +ve and ΔS is –ve 
• d) ΔH is –ve and ΔS is –ve

Answer:   ΔH is +ve and ΔS is –ve 

Question:  The standard free energy change ΔG° is related to K (equilibrium constant) as

• a) ΔG° = –2.303 RT logK
• b) ΔG° = 2.303 RT logK
• c) ΔG° = RT logK
• d) ΔG° = –RT logK

Answer:  ΔG° = –2.303 RT logK

Question: For an endothermic reaction to be spontaneous

• a) ΔG = 0
• b) ΔG > 0
• c) ΔG < 0 
• d) ΔG may be +ve or –ve

Answer:  ΔG < 0 

Question: The sole criterion for the spontaneity of a process is

• a) Tendency to acquire minimum energy
• b) Tendency to acquire maximum randomness
• c) Tendency to acquire minimum energy and maximum randomness
• d) Tendency to acquire maximum stability

Answer: Tendency to acquire maximum stability

Question:  At 27°C the reaction,

proceeds spontaneously because the magnitude of

• a) ΔH = TΔS   
• b) ΔH > TΔS 
• c) ΔH < TΔS 
• d) ΔH > 0 and TΔS < 0

Answer:  ΔH > TΔS 

Question: For two mole of an ideal gas

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question: When an ideal gas is compressed adiabatically and reversibly, the final temperature is

• a) Higher than the initial temperature
• b) Lower than the initial temperature
• c) The same as the initial temperature
• d) Dependent on the rate of compression

Answer: Higher than the initial temperature

Question:  ΔS° will be highest for the reaction

• a)

  

• b)

  

• c)

  

• d)

  

Answer:

Question:   In an irreversible process, the value of

• a) +ve
• b) –ve
• c) Zero
• d) All of these

Answer: +ve

Question: A closed flask contains a substance in all its three states, solids, liquids and vapour at its triple point. In this situation the average KE of the water molecule will be

• a) Maximum in vapour state
• b) Maximum in solid state
• c) Greater in the liquid than in vapour state
• d) Same in all the three states

Answer: Same in all the three states