The answer is 3. The releasing of energy means exothermic reaction. So the ΔH should be negative. And the greatest quantity of energy released means that the greatest number. So according to the table I, the answer is 3.
By direct heating of an element with oxygen : many metals and non-. metals burn rapidly when heated in oxygen or air producing their oxides e.g.
Answer: d
explanation: in both reactants and products there are 2 hydrogen and 2 chlorine atoms
