Consider the elements :
Cs, Ne, I and F
(a) Identify the element that exhibits only negative oxidation state.
(b) Identify the element that exhibits only positive oxidation state.
( c) Identify the element that exhibits both positive and negative oxidation states.
(d) Identify the element which exhibits neither the negative nor does the positive oxidation state.

Explanation

(a) F element exhibits only in negative oxidation state.
(b) CS element exhibits only in positive oxidation state.
( c) .I. can be in both positive and negative oxidation state. .l. has -1, +1, +3, +5, +7 oxidation number.
(d) Ne has zero oxidation state. It does not exhibits negative or positive oxidation state.