Question

Answer the following Questions :-

1. Name three metals which are more reactive than copper.

2. Name the agents which cause corrosion.

3. State two applications of radiation.

4. State two applications of conduction.

5. Give two differences between convection and radiation.

6. Why do we use mercury as a fluid in thermometers?

7. How do land and sea breeze occurs?

8. Why are teapots generally white and shiny?

9. What are the different modes of transfer of heat?​

Answer 1

7) Sea breezes occur during hot, summer days because of the unequal heating rates of land and water. During the day, the land surface heats up faster than the water surface. As the warm air over the land is rising, the cooler air over the ocean is flowing over the land surface to replace the rising warm air.

Answer 2

Answer :

1. Name three metals which are more reactive than copper.

Explanation :-

The three metals which are more reactive than copper are :-

• Magnesium
• Zinc
• Iron

2. Name the agents which cause corrosion.

Explanation :-

The agents which cause corrosion are :-

• Hydrogen
• Oxygen [ moisture ]
• Carbon dioxide

3. State two applications of radiation.

Explanation :-

The two applications of radiation are :-

• People prefer wearing white or light coloured clothes during summer to stay cool, and dark-coloured clothes during winter to stay warm
• The base of cooking utensils is made black to maximize the heat from the fire [ flame ], but the inside of cooking utensils are generally kept shiny to minimize the loss of heat by radiation.

4. State two applications of conduction.

Explanation :-

• In snowy areas the natives make igloo from snow, the air trapped in the snow acts as an insulator and doesn't allow heat from inside to go out.
• Handles of cooking vessels are are made up of insulators [ example :- wood ], so that we can hold them safely.

5. Give two differences between convection and radiation.

Explanation :-

Convection :-

• The mode of transfer of heat in fluids where the molecules actually move from one part of fluid to other.
• Convection doesn't takes place in solids.

Radiation :-

• The transfer of heat from a hot body to a cold body which does not require any medium and directly without heating the space in between.
• Radiation takes place in solids, liquids and gases.

6. Why do we use mercury as a fluid in thermometers?

Explanation :-

We use Mercury as a fluid in thermometer because Mercury expanse and contracts and a liquid metal, as we know that metals are the good conductors of heat.

7. How do land and sea breeze occurs?

Explanation :-

Land breeze and sea breeze are the applications of convection currents in air.

Land breeze :-

• Land breeze flows from the land to sea during night time.

Sea breeze :-

• Sea breeze blows from the sea to land during daytime.

8. Why are teapots generally white and shiny?

Explanation :-

Teapots are generally white and shiny to minimise the loss of heat by radiation. the shine surface reflects the heat back which helps to stay a hot or cold for long period of time.

9. What are the different modes of transfer of heat?

Explanation :-

The different modes of transfer of heat are :-

• Conduction
• Convection
• Radiation.