Write balanced equations for each of the following reactions (some of these are analogous to reactions shown in the chapter).
(a) Aluminum metal reacts with acids to form hydrogen gas.
(b) Steam reacts with magnesium metal to give magnesium oxide and hydrogen.
(c) Manganese(IV) oxide is reduced to manganese(II) oxide by hydrogen gas.
(d) Calcium hydride reacts with water to generate hydrogen gas.