(i)

Properties of a good thermometric liquid

1. It does not wet/cling to the glass tube
2. It has a large temperature range within which it remains a liquid
3. It expands and contracts regularly/uniformly
4. It does not vaporize/condense in the tube
5. It is visible/opaque

(ii)

Examples of a good thermometric liquid

1. Mercury
2. Ethanol/Alcohol

i)

Effects of heat on plastics

1. It melts
2. It burns

ii)

Effects of heat on alcohol

1. It expands
2. It evaporates
3. It boils

iii)

Effects of heat on metal rod

1. It expands
2. It melts
3. It bends

i)

Differences between heat and temperature

ii)

iii)

Conduction

i)

Heat is the energy which causes rise in temperature of bodies while temperature is the degree of hotness or coldness of a body.

ii)

The unit of heat is joules and temperature is kelvin or degree celsius

(i)

Crackling noises are heard from a metal sheet roof when the weather becomes very hot

1. The metal sheet roof expand when heated but the nails which hold it prevent its free movement
2. Bending occurs and the cracking noise is caused by this bending movement

(ii)

Railway tracks are laid with gaps in between their ends

1.Railway tracks are laid with gaps in between their ends to make room for expansion when the tracks are heated
2. This prevents them from bending

(i)

Processes by which heat can be transferred

1. Conduction
2. Convection
3. Radiation

(ii)

Electrical appliances which use thermostat

1. Electric pressing iron
2. Refrigerator
3. Electric cooker
4. Air conditioner
5. Electric water heater
6. Electric oven
7. Medical and scientific incubator

(i)

The temperature remains the same/unchanged/constant

(ii)

1. Conduction
2. Convection
3. Radiation

(iii)

Applications of the expansion of solids in everyday life

1. Railway line gaps
2. Rollers in metal bridges
3. Thermostat
4. Concrete slabs
5. Riveting
6. Fixing wheels

(i)

The heat of the sun reaches the earth by the process of radiation.

(ii)

Heat loss by an aluminium bowl placed on a table is filled with hot water

Heat is lost by conduction and convection.

(iii)

Reason why wood is used as a handle for some cooking utensils

Wood is used as a handle for cooking utensils because it is a bad/poor conductor of heat.

(i)

Effects of heat on a substance

1. Change of state/melts/vapourises
2. Expansion/contraction/change in shape
3. Increasing temperature/decreasing temperature
4. Increase in pressure

(ii)

Potassium permangante crystals dropped into a beaker of water and warmed:

(i)

Convection

Transfer of heat in which warm/heated fluid become less dense and moves up and cold and denser fluid moves down

(ii)

Reasons why convection does occur in solids

1. The molecules/particles of solids are tightly packed together (held by strong bond)
2. The molecules/particles of solids are fixed in position and cannot move around for convection to take place

i)

Modes of heat transfer

1. Conduction
2. Convection
3. Radiation

ii)

Medium for mode of heat transfer

1. Conduction → Solid
2. Convection → Liquid/gas/fluid
3. Radiation → vacuum/no material medium