Science - Class 9

Q61. State any two characteristic properties of a gas.

Or

What are the main characteristics of a gas?

Or

What are the characteristics of gases?

 

Q62. Convert the following temperatures to the Celsius scale.

(a) 300 K       (b) 573 K

 

Q63. Convert the following temperatures to the Kelvin scale.

(a) 25°C        (b) 373°C.

 

Q64. What produces more severe burns, boiling water or steam?

 

Q65. We come to know of what is being cooked in the kitchen without even entering there, by the smell that reaches our nostrils. How does this smell reach us?

 

Q66. Give reasons for the following observation:

The smell of hot sizzling food reaches you several metres away, but to get the smell from cold food you have to go close.

 

Q67. Why is ice at 273 K more effective in cooling than water at the same temperature?

 

Q68. Why does a desert cooler cool better on a hot dry day?

 

Q69. How does the water kept in an earthen pot (matka) become cool during summer?

 

Q70. Why is heat energy needed to melt a solid? What is this heat energy called?

 

Q71. Why does our palm feel cold when we put some acetone or petrol or perfume on it?

 

Q72. Why are we able to sip hot tea or milk faster from a saucer rather than a cup?