91Ó°ÊÓ

Among sodium phosphate, sodium sulphate and sodium chloride the solubility in water decreases as : (a) sulphate \(>\) phosphate \(>\) chloride \(-0\) (b) chloride \(>\) sulphate \(>\) phosphate \(\square\) (c) chloride \(>\) phosphate \(>\) sulphate \(\square\) (d) phosphate \(>\) chloride \(>\) sulphate

\(\mathrm{NH}_{3}\) has a much higher boiling point than \(\mathrm{PH}_{3}\) because: (a) ammonia has larger molecular weight \(\square\) (b) ammonia undergoes umbrella inversion \(\square\) (c) ammonia contains ionic bonds whereas \(\mathrm{PH}_{3}\) contains covalent bond (d) ammonia form hydrogen bonds

The bond lengths and bond angles in the molecules of methane, ammonia and water are given below: This variation in bond angle is a result of (i) the increasing repulsion between hydrogen atoms as the bond length decreases (ii) the number of non-bonding electron pairs in the molecule (iii) a non-bonding electron pair having a greater repulsive force than a bonding electron pair. [P.M.T. (Kerala) 2007] (a) (i), (ii) and (iii) are correct (b) (i) and (ii) are correct (c) (ii) and (iii) are correct - (d) (i) only is correct

The correct stability order of the following resonance structures is: \(\quad\) [I.I.T. 2009] (i) \(\quad \mathrm{H}_{2} \mathrm{C}=\mathrm{N}^{+}=\overline{\mathrm{N}}\) (ii) \(\mathrm{H}_{2} \mathrm{C}^{+}-\mathrm{N}=\overline{\mathrm{N}}\) (iii) \(\mathrm{H}_{2} \overline{\mathrm{C}}-\stackrel{+}{\mathrm{N}} \cong \mathrm{N}\) (iv) \(\mathrm{H}_{2} \overline{\mathrm{C}}-\mathrm{N}=\stackrel{+}{\mathrm{N}}\) (a) (i) \(>\) (ii) \(>(\mathrm{iv})>\) (iii) \(\square\) (b) (i) \(>(\mathrm{iii})>\) (ii) \(>\) (iv) \(\square\) (c) \((\mathrm{i})>(\mathrm{ii})>(\mathrm{iii})>(\mathrm{iv}) \square\) (d) (iii) \(>(\mathrm{i})>(\mathrm{iv})>\) (ii)