Question

Arrange the order of increasing atomic volumes in : (a) Li, Na and
K; (b) C, N and O ; (c) Ca, Sr and Ba.

Answer 1

Li->C->N->O->K->Ca->Sr->Ba

Answer 2

In the "periodic table", there are certain groups and periods. Groups are "vertical columns" whereas periods are "horizontal rows". The atomic volume increases with increasing atomic radii.

As we move down in the group of periodic table, the atomic radii increases, hence, the atomic volume also increases. Across the period, the atomic radii decreases hence the atomic volume also decreases.  

(a) Li < Na < K

(b) O < N < C

(c) Ca < Sr < Ba