Some Important Scientific Reasons

 

1.       Why the food is cooking quicker in a pressure cooker?

Ans. Due to the vapourisation of water, pressure and boiling point of water increases in the pressure cooker , due to which the temperature also increases and food is cooked earlier.

 

2.       The weight of a man on moon is less than the weight on the earth,why?

Ans.Accelaration due to gravity on the moon is less than the acceleration due to gravity on the earth . As the weight of any thing depends on the value of ‘g’ then the weight of a man on moon is less than the weight of the man on the earth.

 

3.       Bad eggs float in water, why ?

Ans. When the density of a bad egg decreases , then it floats in water.

 

4.       Why mercury is used in the thermometer ?

Ans. The mercury is very sensitive to heat and very bright . It does not stick to the wall. This is the reason mercury is used in the thermometer.

 

5.       Why do people lean forward while climbing on a hill ?

Ans. When people climb on a hill their centre of gravity is displaced from their original position and the possibility is arises to fall on the ground. In order to avoid falling , people lean forward to adjust the centre of gravity at their proper places.

 

6.       In cold regions water-pipes are being cracked in winter seaon ,why?

Ans. When the water turns into ice , its volume increases .When in polar regions water is supplied to the pipes in winter the water changes into ice due to severe cold and hence its volume increases which breaks the pipes.

 

7.       Why do water remains cold in earthen pot ?

Ans. There are pores in the earthen pot which allow water to percolate to the outer surface. Here evaporation of water takes place thereby producing cooling effect.

 

8.       Why a flash of lightening is seen before thunder ?

Ans. Since the velocity of light is much higher than the velocity of sound. When there is a lightening , the light reaches the earth first because the velocity of light is higher and sound of thunder is heard later because its velocity is less.

 

9.       In summer the clothes are dried up soon , why ?

Ans. The evaporation process is fast in summer. The is the reason that the wet cloths are dried up very soon.

 

10.    The bubbles of gases emerges when the bottle of soda-water is opened, Why?

Ans. Carbon dioxide gas mixed with the soda-water at high pressure and its packed tightly in the bottles. When the bottle is opened the pressure decreases and the bubbles of carbon dioxide gas come out of the bottle.

 

11.    Argon gas is filled in electric bulb,why ?

Ans. When the bulb is lighted , the filament of the bulb reacts with the oxygen and is destroyed .So the electric bulb is evacuated and filled with the Argon gas which is an inert gas that does not react with the filament.Thats why argon gas is used in electric bulb.

 

12.    The color of leaves is green why?

Ans. A green pigment chlorophyll is found in leaves. Due to the presence of this green pigment the color of the leaves is green.

 

13.    Why do stars twinkle?

Ans. The stars being very far off from the earth, the light-waves have to pass through various layers of air before reaching the earth the stars appear twinkling.

 

14.    Breathing is fast during running,why?

Ans. During running more energy is required by the body . To get the required energy respiration process becomes fast . As being the rate of respiration high, more energy is released.

 

15.    The color of blood is red ,why?

Ans. The color of blood is red due to the presence haemoglobin in the blood.