13. Identify the soft metal among the following:
potassium
Explanation for correct option-
(D) Soft metals are flexible and easy to cut without breaking. Potassium is a soft metal that may be cut with a knife.
Explanation for incorrect option-
(A) Iron is malleable and ductile and shows the properties of metal. It is a hard metal.
(B) Aluminium is a hard metal. It cannot be cut with knife.
(C) Magnesium metal is also hard metal.
Hence, option (D) is the correct answer.