Q73. What is matter? Give examples.

 

Q74. What is the relation between Kelvin scale and Celsius scale of temperature?

 

Q75. Why solid carbon dioxide is also known as dry ice?

 

Q76. Why do gases have neither a fixed shape nor a fixed volume?

 

Q77. When a crystal of copper sulphate is placed at the bottom of a beaker containing water, the water slowly turns blue even without stirring. Why?

 

Q78. What is the physical state of water at -

(a) 25°C (b) 0°C (c) 100°C 

 

Q79. How does perspiration or sweating help keep our body cool on a hot day?

Or

Why do we feel cool after sweating?

Or

Explain how sweating helps to cool the body.

 

Q80. For any substance, why does the temperature remain constant during the change of state?

 

Q81. How can the evaporation of a liquid be made faster?

Or

How can we increase the rate of evaporation?

 

Q82. What are the factors affecting evaporation?

 

Last modified: Wednesday, 1 July 2020, 11:03 PM