Magnesium reacts with an element (X) to form an ionic compound.
If the ground state electronic configuration of (X) is $1{\mathrm{s}}^{2}2{\mathrm{s}}^{2}2{\mathrm{p}}^3$,
the simplest formula for this compound is: 

1. ${\mathrm{Mg}}_2{\mathrm{X}}_3$

2. ${\mathrm{MgX}}_2$

3. ${\mathrm{Mg}}_2\mathrm{X}$

4. ${\mathrm{Mg}}_3{\mathrm{X}}_2$

The correct order of ionic radii is:

1. $H^{-}>H^{+}>H$ $$
2. $N{a}^{+}>F^{-}>O^{2-}$
3. $F^{-}>O^{2-}>N{a}^{+}$
4. $N^{3-}>M{g}^{2+}>A{l}^{3+}$

Be²⁺ is isoelectronic with which of the following ions?
1. $H^{+}$
2. $L{i}^{+}$
3. $N{a}^{+}$
4. $M{g}^{2+}$

Among the following, the most characteristic oxidation states for lead and tin are, respectively:

1. +4, +2

2. +2, +4

3. +4, +4

4. +2, +2

Identify the correct order of the size of the following:

1. $C{a}^{2+}<K^{+}<Ar<S^{2-}<C{l}^{-}$

2. $C{a}^{2+}<K^{+}<Ar<C{l}^{-}<S^{2-}$

3. $Ar<C{a}^{2+}<K^{+}<C{l}^{-}<S^{2-}$

4. $C{a}^{2+}<A{r}^{+}<K^{+}<C{l}^{-}<S^{2-}$

Which one of the following orders is not in accordance with the property stated against?

1. $F_2>C{l}_2>B{r}_2>I_2$ $:$ $Oxidi\sin g$ $power$

2. $Hl>HBr>HCl>HF$ $:$ $Acidic$ $property$ $in$ $water$

3. $F_2>C{l}_2>B{r}_2>I_2$ $:$ $Electronegativity$

4. $F_2>C{l}_2>B{r}_2>I_2$ $:$ $Bond$ $dissociation$ $energy$

For the second-period elements, the correct increasing order of first ionisation enthalpy is:

1. Li < Be < B < C < O < N < F < Ne

2. Li < Be < B < C < N < O < F < Ne

3. Li < B < Be < C < O < N < F < Ne

4. Li < B < Be < C < N < O < F < Ne

Read the following statements (S) and Explanation (E). Choose the correct answers from the codes (1), (2), (3) and (4):

S : Sulphate is estimated as ${\mathrm{BaSO}}_4$ and not as ${\mathrm{MgSO}}_4$.

E : Ionic radius of ${\mathrm{Mg}}^{2+}$ is smaller than ${\mathrm{Ba}}^{2+}$.

1.  S is correct but E is wrong
2.  S is wrong but E is correct
3.  Both S and E are correct and E is correct explanation of S
4.  Both S and E are correct but E is not correct explanation of S

The incorrect order of electronegativity is :