The element with atomic number $14$ is hard and forms acidic oxide and a covalent halide. To which of the following categories does the element belong?

The atomic numbers of three elements $A, B$,and $C$ are $12, 18$,and $20$ respectively. State,giving reason,which two elements will show similar properties.

The following table shows elements represented by the letters $A, B, C, D, E, F, G$ and $H$.

Group	$1$	$2$	$13$	$14$	$15$	$16$	$17$	$18$
Element	$A$	$B$	$C$	$D$	$E$	$F$	$G$	$H$

$(i)$ Which of the elements has the atomic size:
$(a)$ biggest and $(b)$ smallest?
$(ii)$ Which element has valency:
$(a)$ $3$ and $(b)$ zero?

The element with atomic number $14$ is hard and forms acidic oxide and a covalent halide. To which of the following categories does the element belong?

Properties of the elements are given below. Where would you locate the following elements in the periodic table?
$(a)$ $A$ soft metal stored under kerosene.
$(b)$ An element with variable (more than one) valency stored under water.
$(c)$ An element which is tetravalent and forms the basis of organic chemistry.

Which of the given elements $A$,$B$,$C$,$D$ and $E$ with atomic numbers $2$,$3$,$7$,$10$ and $30$ respectively belong to the same period?