# NCERT Class 11 Physics Solutions: Chapter 11 – Thermal Properties of Matter-Part 1

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**Question 11.1:**

The triple points of neon and carbon dioxide are and respectively. Express these temperatures on the Celsius and Fahrenheit scales.

**Answer:**

Kelvin and Celsius scales are related as:

Celsius and Fahrenheit scales are related as:

For neon:

For carbon dioxide:

**Question 11.2:**

Two absolute scales have triple points of water defined to be and . What is the relation between and ?

**Answer:**

Triple point of water on absolute scale

Triple point of water on absolute scale

Triple point of water on Kelvin scale,

The temperature on Kelvin scale is equivalent to on absolute scale

The temperature on Kelvin scale is equivalent to on absolute scale

is triple point of water on scale

is triple point of water on scale

Therefore, the ratio is given as

**Question 11.3:**

The electrical resistance in ohms of a certain thermometer varies with temperature according to the approximate law

The resistance is at the triplepoint of water and at the normal melting point of lead . What is the temperature when the resistance is

**Answer:**

It is given that:

Where,

are the initial resistance and temperature respectively

are the final resistance and temperature respectively

is a constant

At the triple point of water,

Resistance of lead,

At normal melting point of lead,

Resistance of lead,

Substituting these values in equation we get:

For resistance,

Where, is the temperature when the resistance of lead s