Two elements X and Y have valencies of 5 and 3, and 3 and 2, respectively. The elements X and Y are most likely to be respectively :(a) copper and sulphur (b) sulphur and iron(c) phosphorus and nitrogen (d) nitrogen and iron

Correct Answer: (d) nitrogen and iron

Explanation: Two elements X and Y have valencies of 5 and 3, and 3 and 2, respectively. The elements X and Y are most likely to be nitrogen and iron.