Why does every chemical reaction require a certain amount of activation energy?

a. energy is released when the reactants begin to react.

b. energy lost to the environment during the reaction must be replaced.

c. forming the activated complex requires energy,

d. the products have more potential energy than the activated complex.

e. the reactants have less potential energy than the products,

Balance and in which category does it fit in? single or double displacement or synthesis or decomposition? (a) k2 o → k + o2 (b) na + i2 → nai (c) cu(no3 )2 + naoh → cu(oh)2 + nano3 (d) kclo3 → kcl + o2 (e) ca(no3 )2 + hbr → cabr2 + hno3 (f) sn(oh)2 → sno + h2 o (g) p4 + n2 o → p4 o6 + n2 (h) fe + al2 (so4 )3 → feso4 + al (i) alcl3 + na2 co3 → al2 (co3 )3 + nacl (j) c3 h6 + o2 → co2 + h2 o