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Every solid substance melt at a definite temperature on heating. Hence, when we heat ice, the kinetic energy increases and they get separated and free to move.

Thermometer is made on the property of expansion of liquids on heating.

On heating, the air expands, occupying more space and becomes lighter.

Heat does not flow between two objectives

Kinetic energy of particles increases with increase of temperature.

As the pressure increases the boiling point of water also increases. In the pressure cookers the boiling point of water increases due to the pressure created by blocking of the steam by weight. The weight rises up and lets out the steam of the pressure crosses certain limit. Due to the increases in the boiling points the food substances are cooked with in less time. Thus it saves the energy.

Boiling point of liquid increases with external pressure.

The amount of heat energy absorbed at constant temperature by unit mass of a solid to convert into liquid phase is called the specific latent heat of fusion.

It is expressed in units J/kg, erg/g, cal/g, kJ/ kg and kcal/kg.

[Note: Specific latent heat (L) = \(\frac{latent\,heat\,(Q)}{mass\,of\,the\,substance}\)

∴ SI unit of specific latent heat = SI unit of energy / SI unit of mass = J/kg]

When a solid is converted into liquid at constant temperature (melting point of the substance) the amount of heat absorbed by it is called the latent heat of fusion.

Heat is a form of energy. Hence, latent heat is expressed in units joule, erg, calorie or kilocalorie.

Following will absorb heat fast: steel spoon, iron griddle, water, wax. Remaining objects also obsorb heat but very slowly.

Correct answer is: (b) γ = 2α 

Let A₀ and A_t be the areas of cross-section of the tube at temperatures 0 and t respectively,

 I = length of the liquid column (constant)

V₀ and V_t be the volumes of the liquid at temperatures 0 and t respectively,

V₀ = lA₀ V_t = lA_t

V_t = V₀(1 + γt) A_t = A₀(1 + 2αt)

∴ V_t = lA₀(1 + 2αt) = V₀(1 + γt) = lA₀(1 + γt)

or γ = 2α.

i. black

ii. Radiation

iii. solid

iv. reflection

v. conduction

vi. radiation

If the object loses heat energy, ΔT would represent the decrease in temperature.

Correct Answer is: (d) in any process

Rainfall is measured in millimeters by using a rain gauge.

The water vapour present in the air is called humidity.

The heat is needed to raise the temperature of a certain mass of the substance to a certain level by using the equation Q= mSΔT, where ‘S’ is called the specific heat of the substance.

C.G.S. unit of specific heat is cal/g-°C. 

S.l. unit of specific heat is J/kg – K.

1 cal/g-°C = 4.186 x 103 J/Kg – K

Fahrenheit : Temperature is measured in Fahrenheit (°F).

The SI unit of temperature is Kelvin (K).

Kelvin : The SI unit of temperature is Kelvin (K).

Temperature is measured in degrees of Celsius, degrees of Fahrenheit or Kelvin using a thermometer.

Maximum and minimum temperature of a day, air pressure, rainfall, wind speed and humidity are called measuring components of weather.

This process of transfer of heat from source of heat to surface by the motion of particles is called “convection of heat”. In liquids and gases heat is transmitted by mode of convection of heat.

Air pressure is measured in height of mercury level in centimeters.

Transfer of heat is different in different types of materials. Heat gets transferred in three different modes. 

They are 

1. Conduction of heat 

2. Convection of heat 

3. Radiation of heat.

The materials which allow heat to pass through them are called conductors of heat. 

Ex : Aluminum, iron and copper etc.

The floor is laid in small pieces with gaps in between to allow for the expansion during summer. However glass strips can be placed in the gaps.

In the construction of a bridge, steel girders are used. One end of the girder is fixed into the concrete or brick pillars and its other end is not fixed, but it is placed on rollers. The reason is that if there is any rise (or fall) in temperature of atmosphere, the girder can freely expand (or contract) without affecting the pillars.

Correct Answer is: (b) Pt/M 

For thermal equilibrium in the molten state, the rate of absorbing heat = P = the rate of losing heat due to radiation, etc. 

When the power source is turned off, the system continues to lose heat at the same rate, as its temperature does not change.

Therefore, heat lost in time t = Pt = required heat loss for complete solidification = ML, where L = specific latent heat of fusion.

Correct Answer is: (c)

Let L_s = specific latent heat of vaporization,

L_I = specific latent heat of freezing. 

Given, L_s = ηL_I.

Let m = initial mass of water, f = fraction of water frozen.

Mass of vapour formed = m(1 - f), mass of ice formed = m_f.

 m(1 - f)L_s = mfL_I

or 1 - f/f = LI/L_s = 1/η

or η - ηf = f

or f = η/η + 1 . 

Correct Answer is: (b) η/η + 1 

C) increases continuously till it reaches 100° C

A) remains constant

The correct option is (A) remain constant

Correct option is  C) boiling

The correct option is (c) Boiling

The process of transfer of heat in the form of waves is called radiation.

Correct option is  C) freezing

The process of transfer of heat from source of heat to surface by the motion of particles is called “convection of heat”.

The SI unit of temperature is kelvin (K).

A) temperature remains constant

Correct option is  C) x(z – y)

1. Conduction of heat 

2. Convection of heat 

3. Radiation of heat.

1. Water expands on freezing.

2. Condensation is the reverse process of evaporation.

3. Temperature is a measure of thermal equilibrium.

4. Temperature: The degree of hotness or coldness is called temperature.

Correct option is  A) water

There are three modes of transfer of heat. 

(i) Conduction 

(ii) Convection 

(iii) Radiation. 

(i) Conduction “is that mode of transfer of heat, when heat travels from hot end to cold end from particle to particle of the medium, without actual movement of particles.” 

(ii) Convection. “Is a process of transfer of heat by actual move-ment of the medium particles.”

(iii) Radiation. “Is that mode of transfer of heat in which heat directly passes from one body to the other body without heating the medium.”

Gases expand much more than the liquids and the solids. Like liquids, the gases do not have a definite shape, so they also have only the cubical expansion.