During reaction of which metals with cold water, hydrogen gas catches fire?

Q.) During reaction of which metals with cold
water, hydrogen gas catches fire?

(I) Sodium

(II) Calcium

(III) Magnesium

(IV) Potassium

(a) Both (I) and (II)

(b) Both (III) and (IV)

(c) Both (I) and (IV)

(d) Both (II) and (IV)

Ans: (c) Both (I) and (IV)

Explanation: Reaction of both sodium and potassium with cold water is so violent and exothermic that the hydrogen gas evolved catches fire. Reaction of calcium with cold water is less violent whereas magnesium does not react with cold water but reacts with hot water. 2K(s) + 2H2O(l) → 2KOH(aq) + H2(g) + heat energy 2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g) + heat energy

Leave a Reply