Look at the four chemical reactions.

reaction 1: 4na + o2 → 2na2o
reaction 2: 2nacl → 2na + cl2
reaction 3: caco3 → cao + co2
reaction 4: 2kclo33 → 2kcl + 3o2

which statement identifies the reaction that is different from the rest and explains correctly why it is different?

reaction 2, because two ions are interchanged
reaction 2, because two products are formed
reaction 1, because a single product is formed
reaction 1, because a single ion is replaced in a compound