Consider the following statements:
I. There are 18 group and 8 periods in the periodic table.
II. The valency of elements increases from 1 to 4 and then decreases to 0 on moving from left to right in a period.
III. Atomic size, electropositive character, metallic character and basic nature of oxides decrease from left to right in a period.
IV. In a period, electronegativity and electron affinity decreases from left to right.
Which of these is/are correct?
1
II and III
2
I, III and IV
3
III and IV
4
I and IV