11th Physics - Book Back Answers - Unit 9 - English Medium Guides

 

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Tamil Nadu Board 11th Standard Physics - Unit 9: Book Back Answers and Solutions

    This post covers the book back answers and solutions for Unit 9 – Physics from the Tamil Nadu State Board 11th Standard Physics 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 Physics Unit 9 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 9:Kinetic Theory Of Gases

I. Multiple Choice Questions

1. A particle of mass m is moving with speed u in a direction which makes 60° with respect to x axis. It undergoes elastic collision with the wall. What is the change in momentum in x and y direction?

(a) Δp_x = −mu, Δp_y = 0

(b) Δp_x = −2mu, Δp_y = 0

(c) Δp_x = 0, Δp_y = mu

(d) Δp_x = mu, Δp_y = 0

Answer Key:

(a) Δp_x = −mu, Δp_y = 0

2. A sample of ideal gas is at equilibrium.Which of the following quantity is zero?
(a) rms speed
(b) average speed
(c) average velocity
(d) most probable speed
Answer Key:
(c) average velocity

3. An ideal gas is maintained at constant pressure. If the temperature of an ideal gas increases from 100K to 10000K then the V_rms speed of the gas molecules
(a) increases by 5 times
(b) increases by 10 times
(c) remains same
(d) increases by 7 times
Answer Key:
(b) increases by 10 times

4. Two identically sized rooms A and B are connected by an open door. If the room A is air conditioned such that its temperature is 4°C lesser than room B, which room has more air in it?
(a) Room A
(b) Room B
(c) Both room has same air
(d) Cannot be determined
Answer Key:
(a) Room A

5. The average translational kinetic energy of gas molecules depends on
(a) number of moles and T
(b) only on T
(c) P and T
(d) P only
Answer Key:
(a) number of moles and T

6. If the internal energy of an ideal gas U and volume V are doubled then the pressure
(a) doubles
(b) remains same
(c) halves
(d) quadruples
Answer Key:
(b) remains same

7. The ratio γ = $\frac{{\mathrm{C}}_{\mathrm{p}}}{{\mathrm{C}}_{\mathrm{v}}}$ for a gas mixture consisting of 8 g of helium and 16 g of oxygen is (Physics Olympiad -2005)
(a) 23/15
(b) 15/23
(c) 27/17
(d) 17/27
Answer Key:
(c) 27/17

8. A container has one mole of monoatomic ideal gas. Each molecule has f degrees of freedom. What is the ratio of γ = $\frac{{\mathrm{C}}_{\mathrm{p}}}{{\mathrm{C}}_{\mathrm{v}}}$
(a) f 
(b) $\frac{\mathrm{f}}{2}$
(c) $\frac{\mathrm{f}}{\mathrm{f}+2}$
(d) $\frac{\mathrm{f}+2}{\mathrm{f}}$
Answer Key:
(d) $\frac{\mathrm{f}+2}{\mathrm{f}}$

9. If the temperature and pressure of a gas is doubled the mean free path of the gas molecules
(a) remains same
(b) doubled
(c) tripled
(d) quadrapoled
Answer Key:
(a) remains same

10. Which of the following shows the correct relationship between the pressure and density of an ideal gas at constant temperature?

Answer Key:

 

11. A sample of gas consists of μ₁ moles of monoatomic molecules, μ₂ moles of diatomic molecules and μ₃ moles of linear triatomic molecules. The gas is kept at high temperature. What is the total number of degrees of freedom?

(a) [3μ₁ + 7( μ₂ + μ₃)] N_A

(b) [3μ₁ + 7 μ₂ + 6μ₃] N_A

(c) [7μ₁ + 3( μ₂ + μ₃)] N_A

(d) [3μ₁ + 6( μ₂ + μ₃)] N_A

Answer Key:

(a) [3μ₁ + 7( μ₂ + μ₃)] N_A

12. If S_P and S_v denote the specific heats of nitrogen gas per unit mass at constant pressure and constant volume respectively, then (JEE 2007)

(a) S_P - S_v = 28R

(b) S_P - S_v = R/28

(c) S_P - S_v = R/14

(d) S_P - S_v = R

Answer Key:

(b) S_P - S_v = R/28

13. Which of the following gases will have least V_rms speed at a given temperature?
(a) Hydrogen
(b) Nitrogen
(c) Oxygen
(d) Carbon dioxide
Answer Key:
(d) Carbon dioxide

14. For a given gas molecule at a fixed temperature, the area under the Maxwell-Boltzmann distribution curve is equal to
(a) $\frac{\mathrm{PV}}{\mathrm{kT}}$
(b) $\frac{\mathrm{kT}}{\mathrm{PV}}$
(c) $\frac{\mathrm{P}}{\mathrm{NkT}}$
(d) PV
Answer Key:
(a) $\frac{\mathrm{PV}}{\mathrm{kT}}$

15. The following graph represents the pressure versus number density for ideal gas at two different temperatures T₁ and T₂. The graph implies

(a) T₁ = T₂

(b) T₁ > T₂
(c) T₁ < T₂
d) Cannot be determined
Answer Key:
(b) T₁ > T₂
 

II. Short Answer Questions

11th physics

III. Long Answer Questions

11th Physics

IV. Exercise

11th Physics