NEET Practice Questions (MCQs) with Answers & Solutions

(c) "Unununium" At number =111

      It is a transition element. Period number = 7th; Group number = 11

(d) Atomic radius and metallic character decreases from left to right across the period and increases from top to bottom down the group.

(c) P is trivalent non - metal Q is divalent metal hence formula of compound is $P_2{Q}_3$.

(b) Zn is bigger

In (a)  use (z/e) concept for isoelectronic specie.

     In (c) size of neutral atom is greater than its cation.

(a) (a) Sc > Ti > V > Cr (size decrease initially in 3d-series)

     (b) Correct order : Zn > Cu > Co $\approx$Ni

     (c) Correct order : $S^{2-} > C{l}^{-} > N^3 >O^{2-}$

(b) If we consider the opposite process:

    $$\begin{gathered} \left(a\right) F_{\left(g\right)}+e^{-}\to {F^{-}}_{\left(g\right)} ; ∆H_1 \\ \left(b\right) P_{\left(g\right)}+e^{-}\to {P^{-}}_{\left(g\right)} ; ∆H_2 \\ \left(c\right) S_{\left(g\right)}+e^{-}\to {S^{-}}_{\left(g\right)} ; ∆H_3 \\ \left(d\right) C{l}_{\left(g\right)}+e^{-}\to C{l^{-}}_{\left(g\right) }; ∆H_4 \\ Order of energy releases is : ∆H_4>∆H_1>∆H_3>∆H_2 \end{gathered}$$

$So, {P^{-}}_{\left(g\right)}\to e^{‐}; Requires least energy.$

(a) Correct order of electron affinity is : Cl>F>S>O

     Electron affinity of 2nd period non-metals is less than that of respective 3rd period non-metals.

(d) According to Allred and Rochow scale

Electronegativity =$0.359\frac{Z_{eff.}}{r^2}+0.744$

(a) Nitrogen has stable $2p^3$ configuration and also due to high $e^{-}$ charge density at outermost orbital it requires energy to add one extra $e^{-}$ in its outer most shell i.e., its first electron gain enthalpy is positive.

(a) LiF is sparingly soluble at room temperature due to its high lattice energy.