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 $2^{nd}$ ionization energy of $Ca$ is greater than $1^{st}$ ionization energy of it but lower than $2^{nd}$ ionization energy of K.

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

Answer 1

Answer: (C)

$(a)$ Ionic character

$\%ioniccharacter=16(x_A-x_B)+3.5(x_A-x_B{)}^2$

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

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

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

$(d)$ Successive ionization energies are higher for every element. $2^{nd}$ 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.