It is necessary to take proper care of our eyes.
If there is any problem we should go to the eye specialist. Following are some precautions:
(i) Use suitable spectacles.
(ii) Too little and too much light is bad for eyes.
(iii) Do not look at the sun directly.
(iv) Never rub your eyes.
(v) Wash eyes with clean water.
(vi) Always read at the normal distance for vision.

When a body rolls on other body, rolling friction comes into play.

Since the pole star is situated in the direction of the Earth's axis, so it does not appear to move.

The causes of sparking are :
(i) On electric pole, when wires get loose.
(ii) Breaking of electric wire during thunderstorm.
(iii) Loose connection between plug and socket.

The stars, the planets, the moon and many objects in the sky are called celestial obj

(i) Like poles repel each other.
(ii) Unlike poles attract each other.

If two forces act in the opposite directions on an object, the net force acting on it is the difference between the two forces.

After fertilization, the zygote divides repeatedly and travels down the oviduct. As it travels down, many protective layers are formed around it. The hard shell is formed around the developing embryo. The hen finally lays the egg

Endemic species are those species of plants and animals that are found exclusively in a particular area. A particular type of animal or plant may be endemic to a zone, a state or a country e.g., Sal and wild marygoare endemic flora, Bison and the Indian giant squirrel are endemic fauna of the Pachmarhi Biosphere Reserve.

Water is used by fire brigade to extinguish fire as water cools the combustible material so that its temperature is brought below its ignition temperature. This prevents the fire from spreading.

Polyester is actually made up of the repeating units of a chemical called ester.

Farmers can increase the fertility of the soil by :
(i) adding manure and fertilizers.
(ii) crop rotation.
(iii) leaving the field uncultivated in between two crops.

Copper and aluminium

Monomer is the small unit used in the formation of a polymer.

Curd is added to idlis and bhatura to make them soft.

The crops that are cultivated using organic substances like manures, etc and prohibit the use of harmful chemical substances like fertilisers, pesticides, weedicides, etc are called organic foods.

Sodium benzoate and sodium meta bisulphite are special chemicals used as food preservatives.

Yes, cultivator has an advantage as its use saves time as well as labour by digging into a considerable area at the same time.

Traditional methods of irrigation are dhekli and moat and modern methods are sprinkler system and drip system.

Pea and mustard are two examples of rabi crops.