Question

Metal surface reacts with oxygen and the moisture present in air and get coated with:

• A. oxide
• B. carbonate
• C. hydroxide
• D. any of the above

Answer 1

The correct option is D any of the above

Iron metal reacts in moist air by oxidation to give a hydrated iron oxide. This does not protect the iron surface to further reaction since it flakes off, exposing more iron metal to oxidation. This process is called rusting.

Lithium, sodium and potassium all react vigorously with water to form a metal hydroxide and hydrogen:

$metal+water\to metalhydroxide+hydrogen$. The metal hydroxides are strong alkalis.