NCERT Class 11 Physics Chapter 11 Thermal Properties of Matter CBSE Board Sample Problems (For CBSE, ICSE, IAS, NET, NRA 2023)

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VSA

Question 13:

Is the bulb of a thermometer made of diathermic or adiabatic wall?

Answer:

Diathermic

Question 14:

A student records the initial length l, change in temperature and change in length of a rod as follows:

A Student Records
S. No.
1.210
2.110
3.220
4.310

If the first observation is correct, what can you say about observations 2,3 and 4.

Answer:

2 and 3 are wrong, 4th is correct.

Question 15:

Due to difference in conductivity, metals having high conductivity compared to wood. On touch with a finger, heat from the surrounding flows faster to the finger from metals and so one feels the heat. Similarly, when one touches a cold metal the heat from the finger flows away to the surroundings faster.

Answer:

Question 16:

Calculate the temperature which has same numeral value on Celsius and Fahrenheit scale.

Answer:

Question 17:

These days people use steel utensils with copper bottom. This is supposed to be good for uniform heating of food. Explain this effect using the fact that copper is the better conductor.

Answer:

Since has a high conductivity compard to steel, the junction of Cu and steel gets heated quickly but steel does not conduct as quickly, thereby allowing food inside to get heated uniformly.

Junction of Cu and Steel

Question 18:

Find out the increase in moment of inertia I of a uniform rod (coefficient of linear expansion ) about its perpendicular bisector when its temperature is slightly increased by .

Answer:

Question 19:

During summers in India, one of the common practice to keep cool is to make ice balls of crushed ice, dip it in flavoured sugar syrup and sip it. For this a stick is inserted into crushed ice and is squeezed in the palm to make it into the ball. Equivalently in winter, in those areas where it snows, people make snow balls and throw around. Explain the formation of ball out of crushed ice or snow in the light of P – T diagram of water.

Answer:

Refer to the P. T diagram of water and double headed arrow. Increasing pressure at and 1 atm takes ice into liquid state and decreasing pressure in liquid state at and 1 atm takes water to ice state.

When crushed ice is squeezed, some of it melts. Filling up gap between ice flakes. Upon releasing pressure, this water freezes binding all ice flakes making the ball more stable.

P – T Diagram of Water

Question 20:

of water is supercooled to . At this point, due to some disturbance mechanised or otherwise some of it suddenly freezes to ice. What will be the temperature of the resultant mixture and how much mass would freeze?

Answer:

Resultant mixture reaches of ice and rest is water.

Question 21:

One day in the morning, Ramesh filled up bucket of hot water from geyser, to take bath. Remaining was to be filled by cold water (at room temperature) to bring mixture to a comfortable temperature. Suddenly Ramesh had to attend to something which would take some times, say minutes before he could take bath. Now he had two options: (i) fill the remaining bucket completely by cold water and then attend to the work, (ii) first attend to the work and fill the remaining bucket just before taking bath. Which option do you think would have kept water warmer? Explain.

Answer:

The first option would have kept water warmer because according to Newton՚s law of cooling, the rate of loss of heat is directly proportional to the difference of temperature of the body and the surrounding and in the first case the temperature difference is less, so rate of loss of heat will be less.