Classification of elements and Periodicity in properties MCQs for NEET — Chemistry Questions with Answers

(c) Due to inert effect the stability of lower oxidation state gradually increase while stability of higher

      oxidation state gradually decreases down the group in elements of group 13th to 15th. So correct 

      orders are :

       (iii) ${\mathrm{Pb}}^{2+}>{\mathrm{Pb}}^{4+}, {\mathrm{Bi}}^{3+}>{\mathrm{Bi}}^{5+}$

       (v) ${\mathrm{Sn}}^{2+}<{\mathrm{Pb}}^{2+}, {\mathrm{Sn}}^{4+}>{\mathrm{Pb}}^{4+}$

Surface of Al forms ${\mathrm{Al}}_2{\mathrm{O}}_3$ on exposure to air and becomes passive.

Each combustion is exothermic.

${\mathrm{Al}}_2{\mathrm{O}}_3+3\mathrm{C}+{\mathrm{N}}_2 \stackrel{}{\to } 2\mathrm{AlN}+3\mathrm{CO}$

Surface of $\mathrm{Al}$ forms ${\mathrm{Al}}_2{\mathrm{O}}_3$ in nitric acid and becomes passive.

Lead oxide (PbO₂) is amphoteric oxide and thus reacts with both acids and bases.
- PbO₂ reacts with HCl to form PbCl₂ and H₂O.
PbO₂ + 2HCl $\to$ PbCl₂ + H₂O
- PbO₂ reacts with NaOH to form Na₂PbO₃ and H₂O
PbO₂ + 2NaOH $\to$ Na₂PbO₃ + H₂O

-Bond dissociation energy of F₂ is less than that of Cl₂

-Cl has higher E.A. than fluorine

-HF is weaker acid than HCl, due to higher bond energy

The bond energy of F₂ is less than Br₂ due to interelectronic repulsion

Cl₂>Br₂>F₂>I₂

(a) Acidic strength of hydrides increases as the size of central atom increases which weakens the M-H bond. Since, the size increases from S to Te thus acidic strength follows the order

H₂S<H₂Se<H₂Te