(a) Define a combination reaction.
(b) Give one example of a combination reaction which is also exothermic.
(c) Give one example of a combination reaction which is also endothermic.
(a)Reaction in which two or more substances combine to form a single substance are called combination reaction.
(b) C (s) + O2 (g) 
CO2 + Heat
Reaction is exothermic as heat is given from the reaction.
(c) N2 (g) + O2 (g) + Heat 
2NO (g)
Reaction is endothermic as heat is given to the reaction.
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