Question

which of the folowing is not a combination reaction 1 . reaction of hydrogen with nitrogen
2.reaction of quick lime in water
combustion of magnesium in air
4.heating of limestone​

Answer 1

Answer:

4. heating of limestone

Explanation:

heating of limestone is a decomposition reaction

CaCO3(s)→(heat)→Ca O(s)+CO2(g)

limestone when heated becomes Quicklime

this is an example of thermal decomposition.