Chemical Reactions and Equations

One of thee following does not happen during a chemical reaction

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

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

• Formation of new substances with entirely different properties

• A rearrangement of atoms takes place to form new products

When magnesium metal is burned in air, it gives

• White flame

• Dazzling yellow flame

• Dazzling white flame

• Yellow flame

Chemical reaction between zinc and dilute sulphuric acid, which gas is evolved

• Carbon dioxide

• Oxygen

• Nitrogen

• Hydrogen

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

An acid which can decolourise purple coloured potassium permanganate solution is

• Sulphuric acid

• Citric acid

• Carbonic acid

• Hydrochloric acid

Which of the following is not an endothermic reaction

• CaCO3 ----> CaO + CO2

• 2H2O ---> 2H2 + O2

• 6CO2 + 6H2O ----> C6H12O6 + 6O2

• C6H12O6 + 6O2 ---> 6CO2 + 6H2O

One of the following is an exothermic reaction

• Electrolysis of water

• Conversion of limestone into quick lime

• Process of respiration

• Process of photosynthesis

When the solution of substance X is added to a solution of potassium iodide, then a yellow solid separates out from the solution. What substance X is

• H2SO4

• Pb(NO3)2

• BaCl2

• Al2(SO4)3

The chemical reaction between two substances is characterised by a change in colour from orange to green. What are those two substances

• Potassium dichromate and sulphur dioxide

• Potassium permanganate and sulphur dioxide

• Potassium permanganate and lemon juice

• Potassium dichromate and lemon juice

What is the aqueous colour of MgSO4

• Blue

• Greenish yellow

• Brown

• Colourless