Thermal Physics

Samacheer Book Back Questions And Answers For Science Standard 10 “Thermal Physics“

I. Choose the correct answer:
1. The value of universal gas constant
a) 3.81 mol^–1 K^–1
b) 8.03 mol^–1 K^–1
c) 1.38 mol^–1 K^–1
d) 8.31 mol^–1 K^–1

2. If a substance is heated or cooled, the change in mass of that substance is
a) positive
b) negative
c) zero
d) none of the above

3. If a substance is heated or cooled, the linear expansion occurs along the axis of
a) X or –X
b) Y or –Y
c) both (a) and (b)
d) (a) or (b)

4. Temperature is the average _____ of the molecules of a substance
a) difference in K.E and P.E
b) sum of P.E and K.E
c) difference in T.E and P.E
d) difference in K.E and T.E

5. In the Given diagram, the possible direction of heat energy transformation is

a) A ← B,A ← C,B ← C
b) A → B,A → C,B → C
c) A → B,A ← C,B → C
d) A ← B,A → C,B ← C

II. Fill in the blanks:
1. The value of Avogadro number _____.
2. The temperature and heat are _____ quantities.
3. One calorie is the amount of heat energy required to raise the temperature of _____ of water through _____.
4. According to Boyle’s law, the shape of the graph between pressure and reciprocal of volume is _____.

Answers:
1. 6.023 x 10²³ / mol (or) mol^-1
2. Scalar
3. 1 gm, 1°C
4. straight line

III. State whether the following statements are true or false, if false explain why?
1. For a given heat in liquid, the apparent expansion is more than that of real expansion.
2. Thermal energy always flows from a system at higher temperature to a system at lower temperature.
3. According to Charles’s law, at constant pressure, the temperature is inversely proportional to volume.

Answers:
1. False (The real expansion is more (or) less than that of apparent expansion)
2. True
3. False (Volume is directly proportional to temperature at constant pressure)

IV. Match the following:
1. Linear expansion            A. change in volume
2. Superficial expansion     B. hot body to cold body
3. Cubical expansion          C. 1.381 X 10^-23 JK^-1
4. Heat transformation       D. change in length
5. Boltzmann constant        E. change in area

Answers:
1. D
2. E
3. A
4. B
5. C

V. Assertion and reason type questions:
1. Assertion: There is no effects on other end when one end of the rod is only heated.
Reason: Heat always flows from a region of lower temperature to higher temperature of the rod.
a. Both the assertion and the reason are true and the reason is the correct explanation of the assertion.
b. Both the assertion and the reason are true but the reason is not the correct explanation of the assertion.
c. Assertion is true but the reason is false.
d. Assertion is false but the reason is true.

2. Assertion: Gas is highly compressible than solid and liquid
Reason: Interatomic or intermolecular distance in the gas is comparably high.
a. Both the assertion and the reason are true and the reason is the correct explanation of the assertion.
b. Both the assertion and the reason are true but the reason is not the correct explanation of the assertion.
c. Assertion is true but the reason is false.
d. Assertion is false but the reason is true.

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