Zinc is used to protect iron from corrosion because zinc is:

• more electropositive than iron

• cheaper than iron

• a bluish white metal

• a good conductor of heat and electricity

Which one of the following gases is placed second in respect of abundance in the Earth's atmosphere?

• Oxygen

• Hydrogen

• Nitrogen

• Carbon dioxide

Which one of the following is a chemical change?

• Cutting of hair

• Graying of hair naturally

• Swelling of resin in water

• Cutting of fruit

Which one among the following chemicals is used as washing soda?

• Calcium carbonate

• Calcium bicarbonate

• Sodium carbonate

• Sodium bicarbonate

65.

Why is potassium permanganate used for purifying drinking water?

• It kills germs

• It dissolves the impurities

• It is a reducing agent

• It is an oxidizing agent

Molecules of which of the following has cage like structure?

1. Diamond
2. Graphite
3. Fullerenes

Select the correct answer using the code given below:

• 1, 2 and 3

• 2 and 3 only

• 2 only

• 3 only

Temporary hardness in water is due to which one of the following of Calcium and Magnesium?

• Hydrogen carbonates

• Carbonates

• Chlorides

• Sulphates

Stung by hairs of nettle leaves causes burning pain. This is due to the injection of

• Acetic acid

• Methanoic acid

• Sulphuric acid

• Hydrochloric acid

Which one of the following elements is least reactive with water?

• Lithium

• Sodium

• Potassium

• Cesium

Rutherford's alpha-particle scattering experiment was responsible for the discovery of

• Electron

• Proton

• Nucleus

• Helium