What happens to the rate of a reaction when the concentration of reactant is increased?
Rate of reaction will increase.
Greater concentration of reactant will result in greater rate of the reaction. For e.g. granulated zinc reacts with both 1M hydrochloric acid and 2M hydrochloric acid. The rate of evolution of hydrogen gas is faster in case of 2M hydrochloric acid. This is because 2M hydrochloric acid is more concentrated than 1M hydrochloric acid.