Question

Out of the following which metal does not exist in free state?
A. Au
B. Ag
C. Zn
D. Cu

Answer 1

It is used to galvanise other metals, such as iron, due to its unreactive nature to prevent them from rusting. It is also essential for all living things and mainly for the growth of the human body.

Complete step-by-step answer: First, we are going to define the free state of an element.
Those elements which are not combined with or chemically bonded to other elements are called the element in free state. In other words, all the atoms of the element are in free state and have an oxidation number of 0.
Most of the metals which are present in the periodic table are extremely reactive. As a result, these metals are found in chemical compound form in nature. But there are some exceptions, metals which are extremely less reactive can be found not in any sort of compound formation. Due to their less reactive nature they are not affected by the action of other chemicals present in the atmosphere, hence, we can easily find them in their free state in nature.
For example:
Gold
Silver
Copper
Platinum

Zinc is quite reactive and hence they do not occur in the free state. It reacts with atmospheric sulphur to form Zinc sulphide (ZnS), commonly known as zinc blende.

So, the correct option is (C).

Note: The element already has its octet of electrons complete, therefore no bonding is required for their stability. For example, noble gases:
Helium
Neon
Argon
Krypton
Xenon