Question

Which of the following statements is/are wrong?
I) $B{i}^{3+}$ is more stable than $B{i}^{5+}$.
II) $Mn$ shows $+8$ oxidation state.
III) The oxidation state of an element is always less than or equal to its group number.
IV) $s-$Block elements show variable oxidation states.

• A. II and IV
• B. II and III
• C. I, II and III
• D. II, III and IV

Answer 1

The correct option is A II and IV

$Mn$ does not show $+8$ oxidation state as it is having only 7 valence electrons $\left(3d^{5}4s^2\right)$, so it can exhibit maximum of $+7$ oxidation state. Hence, statement II is wrong.
s-Block elements do not show variable oxidation states, it shows single oxidation state as it has only 1 and two electrons in their its valence shell for IA group and IIA group elements respectively, so the oxidation state of IA is $+1$ and IIA is $+2$ only. Hence, this statement is also wrong.

As these two statements are wrong, option $A$$ is correct.