The electronic configuration of an element with the largest difference between the $1^{\mathrm{st} }\mathrm{and} 2^{\mathrm{nd}}$ ionization energies is

1.  $1s^2 2s^2 2p^6$

2.  $1s^2 2s^2 2p^6 3s^1$

3.  $1s^2 2s^2 2p^{6}3s^2$

4.  $1s^2 2s^2 2p^1$

Among the elements Li, N, C and Be, one with the largest atomic radius is

1.  Li

2.  N

3.  C

4.  Be

The first ionisation energy of Na, B, N and O atoms follows the order 

1.  B < Na < O < N

2.  Na < B < O < N

3.  Na < O < B < N

4.  O < Na < N < B

Among ${\mathrm{P}}_2{\mathrm{O}}_5, {\mathrm{As}}_2{\mathrm{O}}_3, {\mathrm{Sb}}_2{\mathrm{O}}_3 \mathrm{and} {\mathrm{Bi}}_2{\mathrm{O}}_3$, the most acidic oxide is:

1.  $P_2{O}_5$

2.  $A{s}_2{O}_3$

3.  $S{b}_2{O}_3$

4.  $B{i}_2{O}_3$

The first four ionization energy values of metal are 191, 587, 872 and 5962 kcal/mol respectively. The number of valence electrons in the element is

1.  1

2.  2

3.  3

4.  5

The outermost electronic configuration of the most electronegative element is 

1.  $n{s}^2, n{p}^3$

2.  $n{s}^2, n{p}^6\left(n-1\right)d^5$

3.  $n{s}^2, n{p}^5$

4.  $n{s}^2, n{p}^6$

Of the following, the ion with the largest size is

1.  $O^{2-}$

2.  $N{a}^{+}$

3.  $F^{-}$

4.  $A{l}^{3+}$

Arrange the first ionization enthalpies of Na, Mg, Al, and Si in ascending order:

1. Na < Mg > Al < Si

2. Na > Mg > Al > Si

3. Na < Mg < Al < Si

4. Na > Mg > Al < Si

Electronic configuration of chalcogens in their outermost orbit is:

1. s² p³

2. s² p⁴

3. s² p⁵

4. s² p⁶

Which of the following is smallest in size?

1. Na⁺

2. F^–

3. O^2–

4. N^3–