Question

Which of the following statements is (are) incorrect?

(i) Percentage ionic character in $CsCl$ bond is $\sim 55\%$ . (Electronegativity values of $Cs$ and $Cl$ are $0.7$ and $3.0$ respectively)

(ii) From $H_{2}O$ to $H_{3}O^{+}$ , the geometry around $O$ atom changes drastically.

(iii) The most stable oxidation state for element with atomic number $113$ is expected to be $+2.$

(iv) The $2^{n d}$ ionization energy of $Ca$ is greater than $1^{s t}$ ionization energy of it but lower than $2^{n d}$ ionization energy of K.

• A. Only i
• B. i, ii, iii
• C. ii, iii
• D. iii, iv

Answer 1

Answer: (C)

$\left(\right.a\left.\right)$ Ionic character

$\% \, i o n i c \, c h a r a c t e r = 16 \left(\right. x_{A} - x_{B} \left.\right) + 3.5 \left(\right. x_{A} - x_{B} \left.\right)^{2}$

where, $x_{A} - x_{B} =$ Difference in electro-negativity of bonded atoms. $16 \times \left(\right. 3.0 - 0.7 \left.\right) + 3.5 \times \left(\right. 3.0 - 0.7 \left.\right)^{2} = 55.32 \%$

$\left(\right.b\left.\right)$ Geometry for both the species is tetrahedral, as in both 'O' is $s p^{3}$ hybridised

$\left(c\right) \, 113=\left[R n\right] \, 5f^{14}6d^{10}7s^{2}7p^{1}=$ Due to inert pair effect $7 s^{2}$ electron do not take part in bond formation, so, most stable oxidation state is $+1.$

$\left(\right.d\left.\right)$ Successive ionization energies are higher for every element. $2^{n d}$ ionization of K happens from $3s^{2}3p^{6}$ configuration which is an inert gas configuration and for $Ca$ it happens from $4s^{1}$ . So, K has higher second ionisation energy than Ca.