Which of the following elements will form an acidic oxide?

Where would you locate the element with electronic configuration $2, 8$ in the Modern Periodic Table?

The elements $A$,$B$,$C$,$D$,and $E$ have atomic numbers $9$,$11$,$17$,$12$,and $13$ respectively. Which pair of elements belongs to the same group?

Write true or false for the statements: Non-metals are electronegative. They tend to form bonds by gaining electrons. As the trends in the electronegativity show,non-metals are found on the right-hand side of the periodic table towards the top.

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.

Given below are some elements of the modern periodic table. Atomic numbers of the elements are given in the parentheses: $A(4), B(9), C(14), D(19), E(20)$.
$(a)$ Select the element that has one electron in the outermost shell. Also,write the electronic configuration of this element.
$(b)$ Which two elements amongst these belong to the same group? Give reason for your answer.
$(c)$ Which two elements amongst these belong to the same period? Which one of the two has a bigger atomic radius?