Question

Li resembles to element X which is not the member of alkali metals. The group of X is?

• A. II
• B. III
• C. IV
• D. I

Answer 1

The correct option is A II

Li resembles to element X which is not a member of alkali metals. The group of X must be II group, because certain elements of 2nd period show similarity with their diagonal elements in the 3rd period as shown below : Thus, Li resembles Mg, Be resembles Al and B resembles Si. This is called diagonal relationship and is due to the reason that these pairs of element have almost identical ionic radii and polarizing power (i.e. charge/size ratio). Element of second period are known as bridge elements.

So Li is I st group element and the diagonal element Mg is II nd group element.
Hence option A is correct.