Chapter 21

Which of the following oxides of nitrogen is a coloured gas? [1987-1 Mark] (a) \(\mathrm{N}_{2} \mathrm{O}\) (b) \(\mathrm{NO}\) (c) \(\mathrm{N}_{2} \mathrm{O}_{5}\) (d) \(\mathrm{NO}_{2}\)

The bonds present in \(\mathrm{N}_{2} \mathrm{O}_{5}\) are : (1986-1 Mark) (a) only ionic (b) covalent and coordinate (c) only covalent (d) covalent and ionic

Show with equations, how the following compound is prepared (equations need not be balanced) : sodium thiosulphate from sodium sulphite. [1982-1 Mark]

Nitrogen dioxide cannot be obtained by heating : [1985-1 Mark] (a) \(\mathrm{KNO}_{3}\) (b) \(\mathrm{Pb}\left(\mathrm{NO}_{3}\right)_{2}\) (c) \(\mathrm{Cu}\left(\mathrm{NO}_{3}\right)_{2}\) (d) \(\mathrm{AgNO}_{3}\)

Gradual addition of KI solution to \(\mathrm{Bi}\left(\mathrm{NO}_{3}\right)\) solution initially produces a dark brown precipitate which dissolves in excess of KI to give a clear yellow solution. Write chemical equations for the above reactions. [1996-2 Marks]

Give reasons for the following : (i) Sulphur dioxide is a more powerful reducing agent in an alkaline medium than in acidic medium. [1992-1 Mark] (ii) Valency of oxygen is generally two whereas sulphur shows valency of two, four and six. [1988-1 Mark] (iii) Sulphur melts to a clear mobile liquid at \(119^{\circ} \mathrm{C}\), but on further heating above \(160^{\circ} \mathrm{C}\), it becomes viscous.

White P reacts with caustic soda. The products are \(\mathrm{PH}_{3}\) and \(\mathrm{NaH}_{2} \mathrm{PO}_{2}\). This reaction is an example of \([1980]\) (a) Oxidation (b) Reduction (c) oxidation and reduction (d) Neutralisation

Mention the products formed in the following : (i) Chlorine gas is bubbled through a solution of ferrous bromide. [1986-1 Mark] (ii) Iodine is added to a solution of stannous chloride. [1986-1 Mark]

. The reddish brown coloured gas formed when nitric oxide is oxidised by air is [1979] (a) \(\mathrm{N}_{2} \mathrm{O}_{5}\) (b) \(\mathrm{N}_{2} \mathrm{O}_{4}\) (c) \(\mathrm{NO}_{2}\) (d) \(\mathrm{N}_{2} \mathrm{O}_{3}\)

Arrange the following in : (i) \(\mathrm{HOCl}, \mathrm{HOClO}_{2}, \mathrm{HOClO}_{3}, \mathrm{HOClO}\) in increasing order of thermal stability. [1988-1 Mark] (ii) increasing bond strength [1986-1 Mark] \(\mathrm{HCl}\). HBr. HF, HI

. The total number of lone pairs of electrons in \(\mathrm{N}_{2} \mathrm{O}_{3}\) is [Adv. 2015]

State with balanced equations what happens when : (i) Sodium iodate is added to a solution of sodium bisulphite. [1990 - 1 Marks] (ii) Sodium chlorate reacts with sulphur dioxide in dilute sulphuric acid medium. [1989-1 Mark] (iii) Sodium bromate reacts with fluorine in presence of alkali. [1989-1 Mark] (iv) Iodate ion reacts with bisulphite ion to liberate iodine. [1988-1 Mark] (v) Sodium iodate is treated with sodium bisulphite solution. [1982-1 Mark]

Among the following, the number of compounds than can react with \(\mathrm{PCl}_{5}\) to give \(\mathrm{POCl}_{3}\) is [2011]\mathrm{O}_{2}, \mathrm{CO}_{2}, \mathrm{SO}_{2}, \mathrm{H}_{2} \mathrm{O}, \mathrm{H}_{2} \mathrm{SO}_{4}, \mathrm{P}_{4} \mathrm{O}_{10}

Give reasons for the following : (i) Bond dissociation energy of \(\mathrm{F}_{2}\) is less than that of \(\mathrm{Cl}_{2}\). [1992-1 Mark] (ii) Fluorine cannot be prepared from fluorides by chemical oxidation. [1985-1 Mark] (iii) Anhydrous \(\mathrm{HCl}\) is a bad conductor of electricity but aqueous \(\mathrm{HCl}\) is a good conductor; [1985-1 Mark] (iv) In the preparation of hydrogen iodide from alkali iodides, phosphoric acid is preferred to sulphuric acid [1982-1 Mark]

In \(\mathrm{P}_{4} \mathrm{O}_{10}\), the number of oxygen atoms bonded to each phosphorus atom is ................

write balanced equation involved in the preparation of (i) Anhydrous aluminium chloride from alumina. (ii) Bleaching powder from slaked lime. (iii) Tin metal from cassiterite (iv) Chlorine from sodium chloride.

The basicity of phosphorous acid \(\left(\mathrm{H}_{3} \mathrm{PO}_{3}\right)\) is \(\ldots \ldots \ldots \ldots . . .\) [1990-1 Mark]

Account for the following. Limit your answer to two sentences (i) Hydrogen bromide cannot be prepared by action of concentrated sulphuric acid or sodium bromide. (ii) When a blue litmus paper is dipped into a solution of hypochlorous acid, it first turns red and then later gets decolourised. [1979]

The H-N-H bond angle in \(\mathrm{NH}_{3}\) is greater than the H-As-H bond angle is \(\mathrm{AsH}_{2}\)

Based on the compounds of group 15 elements, the correct statement(s) is (are) [Adv. 2018](a) \(\mathrm{Bi}_{2} \mathrm{O}_{5}\) is more basic than \(\mathrm{N}_{2} \mathrm{O}_{5}\) (b) \(\mathrm{NF}_{3}\) is more covalent than \(\mathrm{BiF}_{3}\) (c) \(\mathrm{PH}_{3}\) boils at lower temperature than \(\mathrm{NH}_{3}\) (d) The \(\mathrm{N}-\mathrm{N}\) single bond is stronger than the P-P single bond

The compound(s) which generate(s) \(\mathrm{N}_{2}\) gas upon thermal decomposition below \(300^{\circ} \mathrm{C}\) is (are)(a) \(\mathrm{NH}_{4} \mathrm{NO}_{3}\) (b) \(\left(\mathrm{NH}_{4}\right)_{2} \mathrm{Cr}_{2} \mathrm{O}_{7}\) (c) \(\mathrm{Ba}\left(\mathrm{N}_{3}\right)_{2}\) (d) \(\mathrm{Mg}_{3} \mathrm{~N}_{2}\)

The nitrogen oxide(s) that contain(s) N-N bond(s) is(are)(a) \(\mathrm{N}_{2} \mathrm{O}\) (b) \(\mathrm{N}_{2} \mathrm{O}_{3}\) (c) \(\mathrm{N}_{2} \mathrm{O}_{4}\) (d) \(\mathrm{N}_{2} \mathrm{O}_{5}\)

A solution of colourless salt \(\mathrm{H}\) on boiling with excess \(\mathrm{NaOH}\) produces a non-flammable gas. The gas evolution ceases after sometime. Upon addition of \(\mathrm{Zn}\) dust to the same solution, the gas evolution restarts. The colourless salt (s) H is (are)\begin{aligned} &\text { (a) } \mathrm{NH}_{4} \mathrm{NO}_{3}\\\ &\text { (b) } \quad \mathrm{NH}_{4} \mathrm{NO}_{2} \quad \text { (c) } \mathrm{NH}_{4} \mathrm{Cl} \text { (d) }\left(\mathrm{NH}_{4}\right)_{2} \mathrm{SO}_{4} \end{aligned}

White phosphorus \(\left(\mathrm{P}_{A}\right)\) has(a) six P-P single bonds (b) four P-P single bonds (c) four lone pairs of electrons (d) PPP angle of \(60^{\circ}\)

Sodium nitrate decomposes above \(800^{\circ} \mathrm{C}\) to give(a) \(\mathrm{N}_{2}\) (b) \(\mathrm{O}_{2}\) (c) \(\mathrm{NO}_{2}\) (d) \(\mathrm{Na}_{2} \mathrm{O}\)

Nitrogen(I) oxide is produced by:(a) thermal decomposition of ammonium nitrate (b) disproportionation of \(\mathrm{N}_{2} \mathrm{O}_{4}\) (c) thermal decomposition of ammonium nitrite (d) interaction of hydroxylamine and nitrous acid.

Match the following, choosing one item from column \(\mathbf{X}\) and the appropriate item from column \(\mathbf{Y}\). [1983 - 2 Marks] \(\mathbf{X}\) \(\mathbf{Y}\) (i) Haber (a) Activation energy (ii) Graham (b) Diffusion of gases (iii) Arrhenius (c) Octet rule (iv) Lewis (d) Ammonia synthesis

Among the following, the correct statement is (a) Phosphates have no biological significance in humans (b) Between nitrates and phosphates, phosphates are less abundant in earth's crust (c) Between nitrates and phosphates, nitrates are less abundant in earth's crust (d) Oxidation of nitrates is possible in soil

Among the following, the correct statement is (a) Between \(\mathrm{NH}_{3}\) and \(\mathrm{PH}_{3}, \mathrm{NH}_{3}\) is a better electron donor because the lone pair of electrons occupies spherical \(s\)-orbital and is less directional (b) Between \(\mathrm{NH}_{3}\) and \(\mathrm{PH}_{3}, \mathrm{PH}_{3}\) is a better electron donor because the lone pair of electrons occupies \(s p^{3}\) orbital and is more directional (c) Between \(\mathrm{NH}_{3}\) and \(\mathrm{PH}_{3}, \mathrm{NH}_{3}\) is a better electron donor because the lone pair of electrons occupies \(s p^{3}\) orbital and is more directional (d) Between \(\mathrm{NH}_{3}\) and \(\mathrm{PH}_{3}, \mathrm{PH}_{3}\) is a better electron donor because the lone pair of electrons occupies spherical \(s\)-orbital and is less directional

White phosphorus on reaction with \(\mathrm{NaOH}\) gives \(\mathrm{PH}_{3}\) as one of the products. This is a (a) dimerization reaction (b) disproportionation reaction (c) condensation reaction (d) precipitation reaction

Give reason(s) why elemental nitrogen exists as a diatomic molecule whereas elemental phosphorus as a tetraatomic molecule.

A soluble compound of a poisonous element \(M\), when heated with \(\mathrm{Zn} / \mathrm{H}_{2} \mathrm{SO}_{4}\), gives a colourless and extremely poisonous gaseous compound \(N\), which on passing through a heated tube gives a silvery mirror of element \(M\). Identify \(M\) and \(N\). [1997 - 2 Marks]

Draw the structure of \(\mathrm{P}_{4} \mathrm{O}_{10}\) and identify the number of single and double P-O bonds. [1996-3 Marks]

Increasing order of extent of hydrolysis:\(\mathrm{CCl}_{4}, \mathrm{MgCl}_{2}, \mathrm{AlCl}_{3}, \mathrm{PCl}_{5}, \mathrm{SiCl}_{4}\)

Write down the resonance structures of nitrous oxide.\(O R\) Write the two resonance structures of \(\mathrm{N}_{2} \mathrm{O}\) that satisfy the octet rule.

Give reasons for the following : (i) The experimentally determined \(\mathrm{N}-\mathrm{F}\) bond length in \(\mathrm{NF}_{3}\) is greater than the sum of the single covalent bond radii of \(\mathrm{N}\) and \(\mathrm{F}\). [1995 - 2 Marks] (ii) Ammonium chloride is acidic in liquid ammonia solvent. [1991 - 1 Mark] (iii) Phosphine has lower boiling point than ammonia. [1989-1 Mark] (iv) \(\mathrm{H}_{3} \mathrm{PO}_{3}\) is a dibasic acid. [1989-1 Mark] (v) Orthophosphorus acid is not tribasic acid. [1987-1 Mark] (vi) A bottle of liquor ammonia should be cooled before opening the stopper. [1983-1 Mark] (vii) Orthophosphoric acid, \(\mathrm{H}_{3} \mathrm{PO}_{4}\), is tribasic, but phosphorous acid, \(\mathrm{H}_{3} \mathrm{PO}_{3}\), is dibasic. [1982 - 1 Mark]

Give structural formula for the following : (i) Phosphorous acid, \(\mathrm{H}_{3} \mathrm{PO}_{3}\) [1981 - 1 Mark] (ii) Pyrophosphoric acid, \(\mathrm{H}_{4} \mathrm{P}_{2} \mathrm{O}_{7}\) \([1981-1\) Mark \(\mid\)