11th Chemistry - Book Back Answers - Unit 7 - English Medium Guides

 

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Tamil Nadu Board 11th Standard Chemistry - Unit 7 : Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 7 – Chemistry from the Tamil Nadu State Board 11th Standard Chemistry textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

    We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

    By going through this material, you’ll gain a strong understanding of Chemistry Unit 7 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

• 1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following 
• 2 Mark Questions: Answer briefly 
• 3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 11 students! Prepare well and aim for top scores. Thank you!

Unit 7 :Basic Concepts of Chemistry and Chemical Calculations

I. Choose the best answer.

1. The amount of heat exchanged with the surrounding at constant pressure is given by the quantity
a) ΔE 
b) ΔH 
c) ΔS
d) ΔG

Answer Key:
b) ΔH 

 
2. All the naturally occurring processes proceed spontaneously in a direction which leads to
a) decrease in entropy
b) increase in enthalpy
c) increase in free energy
d) decrease in free energy

Answer Key: 
d) decrease in free energy

 
3. In an adiabatic process, which of the following is true?
a) q= w
b) q = 0
c) ΔE=q
d) PΔV=0

Answer Key:
b) q = 0

 
4. In a reversible process, the change in entropy of the universe is
a) > 0
b) ≥0
c) < 0
d) =0
Answer Key:

d) =0 

 
5. In an adiabatic expansion of an ideal gas
a) w=-Δu 
b) w=Δu + ΔH
c) Δu =0
d) w = 0
Answer Key:

 a) w=-Δu 

 
6. The intensive property among the quantities below is
a) mass
b) volume
c) enthalpy
d) $\frac{\mathrm{mass}}{\mathrm{volume}}$
Answer Key:

d) $\frac{\mathrm{mass}}{\mathrm{volume}}$

$\frac{\mathrm{ }}{}$ 
7. An ideal gas expands from the volume of 1x10^{- 3}m³ to 1 x10 ^{- 2} m³ at 300 K against a constant pressure at 1 x10⁵ Nm^{- 2} .The work done is
a)-900 J
b) 900 kJ
c) 270 kJ
d)-900 kJ
Answer Key:

a)-900 J 

 
8. Heat of combustion is always
a) positive
b) negative
c) zero
d) either positive or negative
Answer Key:

 b) negative

 
9. The heat of formation of CO and CO₂ are - 26.4 kCal and - 94 kCal, respectively. Heat of combus-tion of carbon monoxide will be
a) +26.4 kcal
b) -67.6 kcal
c) -120.6 kcal
d) +52.8 kcal
Answer Key:

b) -67.6 kcal

  
10. C(diamond) → C(graphite), ΔH = - ve this indicates that
a) graphite is more stable than diamond
b) graphite has more energy than diamond
c) both are equally stable
d) stability cannot be predicted
Answer Key:

a) graphite is more stable than diamond 

11. The enthalpies of formation of Al₂O₃ and Cr₂O₃ are - 1596 kJ and -1134 kJ, respectively. ΔH for the reaction 2Al + Cr₂O₃ →2Cr + Al₂O₃ is

a)-1365 kJ
b) 2730 kJ
c)-2730 kJ
d)-462 kJ
Answer Key:

d)-462 kJ 

 
12. Which of the following is not a thermodynamic function?
a) internal energy
b) enthalpy
c) entropy
d) frictional energy
Answer Key:

d) frictional energy 

 
13. If one mole of ammonia and one mole of hydrogen chloride are mixed in a closed container to form ammonium chloride gas, then
a) ΔH > ΔU
b ΔH - ΔU = 0
c) ΔH + ΔU = 0
d) ΔH < ΔU
Answer Key:

d) ΔH < ΔU 

 
14. Change in internal energy, when 4 kJ of work is done on the system and 1 kJ of heat is given out by the system is
a) +1kJ
b) -5 kJ
c) +3 kJ
d) -3 kJ
Answer Key:

c) +3 kJ 

 
15. The work done by the liberated gas when 55.85 g of iron (molar mass 55.85gmol^-1  ) reacts with hydrochloric acid in an open beaker at ${25}^{\circ }\mathrm{C}$
a) -2.48 kJ
b) -2.22 kJ
c) + 2.22kJ
d) + 2.48kJ
Answer Key:

a) -2.48 kJ

  
16. The value of ΔH for cooling 2 moles of an ideal monatomic gas from ${125}^{\circ }\mathrm{C}$ to ${25}^{\circ }\mathrm{C}$ at constant pressure will be [given Cp=$\frac{5}{2}$R]
a) -250 R
b) -500 R
c) 500 R
d) + 250 R
Answer Key:

b) -500 R 

 

17. Given that C(g) + O₂(g) → CO₂(g) $\mathrm{\Delta }{\mathrm{H}}^{\circ }$ = - a kJ; 2CO(g) + O₂(g) → 2CO₂(g) $\mathrm{\Delta }{\mathrm{H}}^{\circ }$ = - bkJ; Cal-culate the $\mathrm{\Delta }{\mathrm{H}}^{\circ }$ for the reaction C(g) + 1/2O₂(g) → CO(g)

a)$\frac{\mathrm{ b}+2\mathrm{a}}{2}$

b) 2a - b

c) $\frac{2\mathrm{a}-\mathrm{b}}{2}$

d) $\frac{\mathrm{b}-2\mathrm{a}}{2}$

Answer Key: 

d) $\frac{\mathrm{b}-2\mathrm{a}}{2}$

$\frac{\mathrm{ }}{}$

18. When 15.68 litres of a gas mixture of methane and propane are fully combusted at   $0^{\circ }\mathrm{C}$ and 1 atmosphere, 32 litres of oxygen at the same temperature and pressure are consumed. The amount of heat of released from this combustion in kJ is (ΔH_C(CH₄) =  890kJmol -1 and ΔH_C (C₃H₈) = - 2220kJmol^{- 1})
a) -889 kJ
b) -1390 kJ
c) -3180 kJ
d) - 632.68kJ
Answer Key:

d) - 632.68kJ 

 
19. The bond dissociation energy of methane and ethane are 360 kJ mol^{- 1}and 620 kJ mol^{- 1} respec-tively. Then, the bond dissociation energy of C-C bond is
a) 170kJmol^{- 1}
b) 50kJ mol^{- 1}
c) 80kJmol^{- 1}
d) 220 kJmol^{- 1}
Answer Key:

c) 80kJmol^{- 1} 

 
20. The correct thermodynamic conditions for the spontaneous reaction at all temperature is (NEET Phase - I)
a) ΔH and ΔS > 0
b) ΔH < 0 and ΔS < 0
c) ΔH > 0 and ΔS = 0
d) ΔH > 0 and ΔS > 0
Answer Key:

a) ΔH and ΔS > 0 

 
21. The temperature of the system, decreases in an
a) Isothermal expansion
b) Isothermal Compression
c) adiabatic expansion
d) adiabatic compression
Answer Key:

c) adiabatic expansion 

 
22. In an isothermal reversible compression of an ideal gas the sign of q. ΔS and w are respectively
a) +,-,-
b) -, +,-
c) +,-,+
d) -,-,+
Answer Key:

d) -,-,+ 

 
23. Molar heat of vapourisation of a liquid is 4.8 kJmol^{- 1}. If the entropy change is 16J mol^{- 1} K^-1the boiling point of the liquid is
a) 323 K
b) ${27}^{\circ }\mathrm{C}$
c) 164 K
d) 0.3 K
Answer Key:

b) ${27}^{\circ }\mathrm{C}$

$\mathrm{ }$ 
24. AS is expected to be maximum for the reaction

a) Ca(S) + 1/2 O₂(g) → CaO(S)

b) C(S) + O₂(g) → CO₂(g)

c) N₂(g) + O₂(g) → 2NO(g)

d) CaCO₃(S) → CaO(S) + CO₂(g)

Answer Key:

d) CaCO₃(S) → CaO(S) + CO₂(g)

  
25.The values of ΔH and ΔS for a reaction are respectively 30 kJmol^{- 1}and 100 J K^-1mol^{- 1}Then the temperature above which the reaction will become spontaneous is
a) 300 K
b) 30 K
c) 100 K
d) ${20}^{\circ }\mathrm{C}$
Answer Key:
a) 300 K

 

II. Short Answer Questions

11th Chemistry

III. Long Answer Questions

11th Chemistry

IV. Exercise

11th Chemistry