Chemical reaction and equation

........ is a chemical change

• Transformation of ice into water

• Cooking of food

• Evaporation of water

• none

Which among the following is(are) double displacement reaction(s)?(i) Pb + CuCl2 → PbCl2 + Cu (ii) Na2SO4 + BaCl2 → BaSO4 + 2NaCl (iii) C + O2 → CO2 (iv) CH4 + 2O2 → CO2 + 2H2O

• (i) and (iv)
• (ii) only
• (i) and (ii)
• (iii) and (iv)

When I want to balance a chemical equation, this is the only number that I can change.

• Subscript

• Coefficient

• Elemental Symbol

• Yields

Oxidation is a process which involves

• addition of oxygen

• addition of hydrogen

• removal of oxygen

• removal of nitrogen

A substance added to food containing fats and oils is called:

• Oxidant

• Rancid

• Coolant

• Antioxidant

In which of the following process a chemical reaction has taken place?

• Ice melts into water

• A wet shirt got dried in sunlight

• A brown layer is formed over iron rod kept in air

• sugar getting dissolved in water

The reaction in which two compound exchange their ions to form two new compounds is called

• displacement reaction

• combination reaction

• redox reaction

• double displacement reaction

In the following equation:

Na₂CO₃ + xHCI -> 2NaCI +CO₂ + H₂O, the value of x is

• 1

• 2

• 3

• 4

Which of the following does not corrode when exposed to the atmosphere-

• Fe

• Cu

• Au

• Ag

Rusting of an iron is an example of :

• Reduction

• Ionization

• Oxidation

• Dissociation