One method of increasing the chances of particles colliding during a reaction is to... 1)decrease temperature
2) decrease concentration
3)increasing concentration
4)use a catalyst

3

Explanation:

Increasing concentration

in theory, limestone is composed principally of the compound calcium carbonate - caco3, but in reality this compound is deposited in conditions involving a number of other compounds as impurities so it ends up being a mixture of many compounds.

hope this : -)

tony (lordcaos066)