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

Answer:

1. IRON, ALUMINUM , ZINC.
2. Causes of Corrosion

Causes of CorrosionMetal corrodes when it reacts with another substance such as oxygen, hydrogen, an electrical current or even dirt and bacteria. Corrosion can also happen when metals like steel are placed under too much stress causing the material to crack.

3. The following are the two applications of infrared radiation : -

The following are the two applications of infrared radiation : -1. It is used for night vision and security cameras as Infrared Radiation is visible in daytime or night-time. 

The following are the two applications of infrared radiation : -1. It is used for night vision and security cameras as Infrared Radiation is visible in daytime or night-time. 2. Police use it to catch criminals, army use it to detect enemy.

4. 1. A shirt is placed on an ironing board to be ironed. Heat from the iron is conducted to the shirt.

2. The engine of a car is turned on, and the hood becomes warm due to the conduction of heat from the engine to the hood of the car.

Answer 2

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

Three metals which are more reactive then are iron, aluminium and zinc.

(2) Name the agents which cause corrosion.

Two agents of Corrosion are :

• Moisture
• Oxygen

(3) State two applications of radiation.

Two applications of Radiation :

• Radiological imaging- X- Rays/Ct scan
• Used for Treatment of Cancer

(4) State two applications of conduction.

Two applications of Convection :

• Helps in overall transfer of heat between two bodies. - Can warm up back muscles using heating pad
• Spreads heat energy through the body in all directions. - Can heat up the engine when a vehicle is turned on and ignited.

(5) Give two differences between convection and radiation.

Convection :

• Convection will only take place in fluids.
• Convection takes place when there is a difference in density. The heated atoms of the fluid rise up and heat the other atoms.

Radiation :

• Radiation does not require any medium and heat is transferred through electromagnetic waves.
• All objects of more than -273.15 degree Celsius do heat transfer through the process radiation.

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

We use Mercury as a fluid in Thermometers because

• Because mercury is only in liquid state at room temperature.
• Mercury have high coefficient of expansion.
• With the change in temperature, mercury expands and contracts.

(7) How do land and sea breeze occurs?

During the day, the land gets heated faster than the water. The air over the land becomes becomes hotter and rises up. The cooler air from the sea rushes towards the land to takes its place. The air from sea is called Sea breeze.

At night, The the water cools down more slowly than the land. So, the cool air from the land moves towards the sea. This is called as Land breeze.

(8) Why are teapots generally white and shiny?

Teapots are generally white and shiny because, white and shiny coloured objects are the bad absorbers of heat and good radiators of heat, and which helps hot things hot for long time.

(9) What are the different modes of transfer of heat?

The three different modes of transfer of heat are :

• Conduction
• Convection
• Radiation