(a) State Modem Periodic Law.
(b) Elements A, B, C and D have atomic number 1, 8,11 and 19 respectively. Choose the odd element and give reason for your answer.
(a) The properties of elements are the periodic function of their atomic numbers.
(b) Odd element - B having atomic number-8. Reason-B has 6 electrons in valence shell but A, C and D have one electron in their valence shell.