## Classification of Elements and Periodicity in Properties Questions and Answers Part-5

1. Which of the following orders is correct for the first ionization potential of B, C and N?
a) B > C > N
b) N > C > B
c) N > C < B
d) N < C < B

Explanation: Due to stable electronic configuration and effective nuclear charge. IE1 of N > C > B

2. Consider the following changes
$A\rightarrow A^{+}+e^{-}:E_{1}$     and $A^{+} \rightarrow A^{2+}+e^{-}:E_{2}$
The energy required to pull out the two electrons are $E_{1} and E_{2}$    respectively. The correct relationship between two energies would be
a) $E_{1} < E_{2}$
b) $E_{1}=E_{2}$
c) $E_{1}>E_{2}$
d) $E_{1}$ $\geq$ $E_{2}$

Explanation: IE1 is always less than IE2 .

3. Which of the following isoelectronic ions has the lowest ionization energy?
a) $K^{+}$
b) $Ca^{2+}$
c) $CI^{-}$
d) $S^{2-}$

Explanation: Amongst the isoelectronic species, the size of S2– is largest hence its IE will be the lowest.

4. The decreasing order of the ionization potential of the following elements is
a) Ne > Cl > P > S > Al > Mg
b) Ne > Cl > P > S > Mg > Al
c) Ne > Cl > S > P > Mg > Al
d) Ne > Cl > S > P > Al > Mg

Explanation: Closed shell (Ne), half filled (P) and completely filled configuration (Mg) are the cause of higher value of I.E

5. The electronic configuration of elements A, B and C are $\left[He\right]2s^{1},\left[Ne\right]3s^{1} and \left[Ar\right]4s^{1}$respectively. Which one of the following order is correct for $IE_{1}\left(kJ mol^{-1}\right)$     of A, B and C?
a) A > B > C
b) C > B > A
c) B > C > A
d) C > A > B

Explanation: A > B > C

6. The set representing the correct order of first ionization potential is
a) K > Na > Li
b) Be > Mg > Ca
c) B > C > N
d) Ge > Si > C

Explanation: Be > Mg > Ca

7. The correct order of ionization energies is
a) Zn < Cd < Hg
b) Hg < Cd < Zn
c) Ar > Ne > He
d) Cs < Rb < Na

Explanation: Cs < Rb < Na

8. Which of the order for ionization energy is correct?
a) Be < B < C < N < O
b) B < Be < C < O < N
c) Be > B > C > N > O
d) B < Be < N < C < O

Explanation: B < Be < C < O < N

9. First ionization potential will be maximum for
a) Uranium
b) Hydrogen
c) Lithium
d) Iron