Question

Why does iron or zinc not occur free in nature?

Answer 1

Some elements that are very reactive cannot occur in the free state like zinc and iron. Due to their high reactivity nature, they always occur in the ores as carbonates, sulfides, and oxides. Both elements can easily lose electrons and undergo oxidation which reveals that these are highly reactive.

Complete answer:
Chemical elements in the periodic table are arranged in four blocks namely s, p, d, and f blocks. s-block consists of two groups i.e., $1$ and $2$ . The p-block consists of groups from $13$ to $18$ . d-block consists of the groups from $3$ to $12$ and this block is placed between the blocks s and d. d-block was divided into three series $3d,4d,$ and $5d$ series.
Iron is an element with atomic number $26$ , it is a metal that can easily undergo oxidation and combines with elements like oxygen which is a non-metal.
Zinc is an element with atomic number $30$ , it is also a metal that can easily lose electrons.
Both elements are highly reactive, in the reactivity series also these were placed at the top only. Due to this high reactivity, they always exist as a combined state and are not found in a free state.

Note:
Both metals occur in the form of oxides, carbonates, and sulfides. The principal ore of zinc is zinc blende which is simply known as zinc sulfide and calamine which is zinc silicate. Due to high reactivity, these two metals exist as a combination with non-metals.