(a) Atomic size increases from left to right across a period.
(b) Ionization potential increases from left to right across a period.
(c) Electron affinity increases going down a group.
(d) Electro-negativity increases going down a group.
Correct Answer: (b) Ionization potential increases from left to right across a period.
Explanation: With the reference to the variation of properties in the Periodic table, across a period the ionization potential increases from left to right.