Which of the following statements is incorrect?

1.	Van der Waals' radius of iodine is more than its covalent radius.
2.	All isoelectronic ions belong to the same period of the periodic table.
3.	$\mathrm{I}.{\mathrm{E}}_1$ of N is higher than that of O while $\mathrm{I}.{\mathrm{E}}_2$ of O is higher than that of N.
4.	The electron affinity N is almost zero while that of P is 74.3 kJ $mo{l}^{-1}$

Aqueous solutions of two compounds $M_1-O-H and M_2-O-H$ are prepared in two different beakers. If, the electronegativity of $M_1=3.4 , M_2=1.2, O=3.5 and H=2.1,$ then the nature of two solutions will be respectively:

(a) acidic, basic             (b) acidic, acidic

(c) basic, acidic             (d) basic, basic

First three ionisation energies (in kJ/mol) of three representative elements are given below:

Element     $I{E}_1$                    $I{E}_2$                   $I{E}_3$

P               495.8                4562                  6910
Q               737.7               1451                   7733
R               577.5                1817                  2745

Then incorrect option is :

1. Q: Alkaline earth metal.

2. P: Alkali metal.

3. R: s-block element.

4. All three: P,Q & R belong to the same period.

If the ionization enthalpy and negative electron gain enthalpy of an element are 275 and 86 kcal $mo{l}^{-1}$ respectively, then the electronegativity of the element on the Pauling scale is:

1. 2.8                                     

2. 0.0

3. 4.0                                     

4. 2.6

The incorrect statement is:

(1) The second ionisation energy of Se is greater than that of second ionisation energy of As 

(2) The first ionisation energy of $C^{2+}$ ion is greater than that of first ionisation energy of $N^{2+}$ ion

(3) The third ionisation energy of F is greater than that of third ionisation energy of O

(4) Helogens have highest I.E. in respective period

Consider the following ionisation reactions :

I.E. (kJ $mo{l}^{-1}$)

$A_{\left(g\right)}\to A_{\left(g\right)}^{+}+e^{-} , A_1$
$B_{\left(g\right)}^{+}\to B_{\left(g\right)}^{2+}+e^{-}, B_2$
$C_{\left(g\right)}^{+}\to C_{\left(g\right)}^{2+}+e^{-}, C_2$
$B_{\left(g\right)}\to B_{\left(g\right)}^{+}+e^{-}, B_1$
$C_{\left(g\right)}\to C_{\left(g\right)}^{+}+e^{-}, C_1$
$C_{\left(g\right)}^{2+}\to C_{\left(g\right)}^{3+}+e^{-}, C_3$

If monovalent positive ion of A, divalent positive ion of B and trivalent positive ion of C have zero electron. Then incorrect order of corresponding I.E. is :

(1) $C_3>C_2>B_2$                       

(2) $B_1>A_1>C_1$

(3) $C_3>C_2>B_2$                       

(4) $B_2>C_3>A_1$

The incorrect match among the following options is : 

1.$$ $\left[\mathrm{Ar}\right]3{\mathrm{d}}^{5}4{\mathrm{s}}^1\to$ $4^{\mathrm{th}}$ $\mathrm{period},$ $6^{\mathrm{th}}$ $\mathrm{group}$

2. $$ $\left[\mathrm{Kr}\right]4{\mathrm{d}}^{10}\to$ $5^{\mathrm{th}}$ $\mathrm{period},$ ${12}^{\mathrm{th}}$ $\mathrm{group}$

3. $$ $\left[\mathrm{Rn}\right]6{\mathrm{d}}^{2}7{\mathrm{s}}^2\to$ $7^{\mathrm{th}}$ $\mathrm{period},$ $3^{\mathrm{th}}$ $\mathrm{group}$

4. $$ $\left[\mathrm{Xe}\right]4{\mathrm{f}}^{14}5{\mathrm{d}}^{2}6{\mathrm{s}}^2\to$ $6^{\mathrm{th}}$ $\mathrm{period},$ $4^{\mathrm{th}}$ $\mathrm{group}$

Which of the following order is correct for the property mentioned in brackets?

$\left(a\right) S^{2-}>C{l}^{-}>K^{+}>C{a}^{2+}$                 (Ionisation energy)

$\left(b\right) C<N<F<O$                              (2nd Ionisation energy)

$\left(c\right) B>Al>Ga>In>Tl$                     (Electronegativity)

$\left(d\right)N{a}^{+}>L{i}^{+}>M{g}^{2+}>B{e}^{2+}>A{l}^{3+}$    (Ionic radius)

${\mathrm{IP}}_1$ and ${\mathrm{IP}}_2$ for Mg are 178 Kcal mol^–1 and 348 Kcal ${\mathrm{mol}}^{-1}$, respectively. The energy required for the reaction, $\mathrm{Mg}\to {\mathrm{Mg}}^{2+}$ $+$ $2{\mathrm{e}}^{-}$ will be:

1. +170 Kcal ${\mathrm{mol}}^{-1}$

2. +526 Kcal ${\mathrm{mol}}^{-1}$

3. –170 Kcal ${\mathrm{mol}}^{-1}$

4. –526 Kcal ${\mathrm{mol}}^{-1}$

Incorrect statement about characteristics regarding halogens is :

1. Ionization energy decreases with increase in atomic number.

2. Electronegativity decreases with increase in atomic number.

3. Electron affinity decreases with increase in atomic number.

4. Enthalpy of fusion increases with increase in atomic number.