Question

When the atom Li, Be, B and Na are arranged in order of increasing atomic radius, what is the correct order ?

• A. B, Be, Li, Na
• B. Li, Be, B Na
• C. Be, Li, B, Na
• D. Be, B, Li, Na

Answer 1

Answer: (A)

B, Be, Li, Na

Moving from left to right along a period leads to decrease in size of atomic radius. Moving down a group from top to bottom leads to increase in size. Among the given species, $Na$ is the largest. Using the reasoning from above, we have,
$B<Be<Li<Na$.