On moving from left to right in a period of the periodic table, the atomic number of elements increases. What happens to the size of atoms of elements on moving from left to right in a period?

The element which forms a basic oxide has the atomic number of:

Which one of the following does not increase while moving down the group of the periodic table?

Which of the following set of elements is written correctly in the order of their increasing metallic character?

The atomic numbers of the three elements X, Y and Z are 2, 6 and 10 respectively.

(i) Which two elements belong to the same group?

(ii) Which two elements belongs to the same period?

Give reasons for your choice.