Chemical reactions and Equations

1 one of the following does not happen during a chemical reaction. This is

• Breaking of old chemical bonds and formation of new chemical bonds

• Formation of new substances with entirely different properties

• Atoms of one element change into those of another element to form new products.

• Rearrangement of atoms takes place to form new products.

2. Which of the following does not involve a chemical reaction?

• Digestion of food in our body

• Process of respiration

• Burning of candle wax when heated

• Melting of candle wax on heating

ou are given the solution of lead nitrate. In order to obtain a yellow precipitate you should mix with it a solution of potassium -----------------------

An acid which can decolourise purple coloured potassium permanganate solution is

• Sulphuric acid

• Hydrochloric acid

• Citric acid

• Carbonic acid

5.The chemical reaction between quicklime and water is characterized by

• Evolution of hydrogen gas

• Formation of slaked lime precipitate

• Change in temperature of mixture

• Change in colour of the product

6.The chemical equation are balanced to satisfy one of the following laws in chemical reactions. This law is known as

7.One of the following is an exothermic reaction. This is

• Electrolysis of water

• Conversion of limestone into quicklime

• Process of respiration

• Process of photosynthesis

8.Which of the following is not an endothermic reaction?

• CaCO3———> CaO + CO2

• 2H2O——>2H2 + O2

• 6CO2 + 6H2O——> C6H12O6 + 6O2

• C6H12O6 + 6O2——-> 6CO2 + 6H2O

9.The removal of oxygen from a substance is called

• Oxidation

• Corrosion

• Rancidity

• Reduction

10.In a context of redox reactions, the removal of hydrogen from a substance is known as

• Oxidation

• Reduction

• Dehydration

• Dehydrogenation