## Classification of Elements and Periodicity in Properties Questions and Answers Part-7

1. The cause of diagonal relationship is
a) similar electronegativities
b) similar ionic or atomic radii
c) similar polarizing power of ions
d) All the three

Explanation: The cause of diagonal relationship is similar polarizing power of ions

2. Variable valency is generally exhibited by
a) representative elements
b) transition elements
c) non-metallic elements
d) metallic elements

Explanation: Variable valency is generally exhibited by transition elements

3. Which of the following elements does not belong to first transition series?
a) Fe
b) V
c) Ag
d) Cu

Explanation: Ag

4. In the periodic table, with the increase in atomic number, the metallic character of an element
a) decreases in a period and increases in a group
b) increases in a period and decreases in a group
c) increases both in a period and the group
d) decreases both in a period and the group

Explanation: decreases in a period and increases in a group

5. Identify the correct order of the size of the following
a) $Ca^{2+}<K^{+}<Ar<Cl^-<S^{2-}$
b) $Ar<Ca^{2+}<K^{+}<Cl^-<S^{2-}$
c) $Ca^{2+}<Ar<K^{+}<Cl^{-}<S^{2-}$
d) $Ca^{2+}<K^{+}<Ar<S^{2-}<Cl^{-}$

Explanation: For isoelectronic species, size of anion increases as negative charge increases whereas size of cation decreases with increase in positive charge. Further ionic radii of anions is more than that of cations. Thus the correct order is $Ca^{++}<K^{+}<Ar<CI<S^{--}$

6. In which of the following electronic configuration an atom has the lowest ionisation enthalpy?
a) $1s^{2}2s^{2}2p^{3}$
b) $1s^{2}2s^{2}2p^{5}3s^{1}$
c) $1s^{2}2s^{2}2p^{6}$
d) $1s^{2}2s^{2}2p^{5}$

Explanation: $1s^{2}2s^{2}2p^{5}3s^{1}$

7. Which one of the following ionic species has the greatest proton affinity to form stable compound?
a) $NH_2^-$
b) $F^{-}$
c) $I^{-}$
d) $HS^{-}$

Explanation: Proton affinity decreases in moving across the period from left to right due to increase in charge, within a group the proton affinities decreases from top to bottom. Nitrogen family > Oxygen family > Halogens

8. The stability of + 1 oxidation state increases in the sequence:
a) Tl < In < Ga < Al
b) In < Tl < Ga < Al
c) Ga < In < Al < Tl
d) Al < Ga < In < Tl

Explanation: The stability of +1 oxidation state increases from aluminium to thallium i.e. Al < Ga < In < Tl

9. Amongst the elements with following electronic configurations, which one of them may have the highest ionization energy?
a) $Ne\left[3s^{2}3p^{2}\right]$
b) $Ar\left[3d^{10}4s^{2}4p^{3}\right]$
c) $Ne\left[3s^{2}3p^{1}\right]$
d) $Ne\left[3s^{2}3p^{3}\right]$