Question

Elements having valency 'one' are :

(a) always metals

(b) always non-metals

(c) always metalloids

(d) either metals or non-metals

Answer 1

(d) either metals or non metals

Elements with valency 1 can be either metals or non-metals.
When an atom loses one electron to gain stability, it is a metal. When an atom gains an electron to complete its octet it is a non-metal.