Chapter 16

What is expected to happen when phosphine gas is mixed with chlorine gas? (a) the mixture only cools down (b) \(\mathrm{PCl}_{3}\) and \(\mathrm{HCl}\) are formed and the mixture warms up (c) \(\mathrm{PCl}_{5}\) and \(\mathrm{HCl}\) are formed and the mixture cools down (d) \(\mathrm{PH}_{3} \mathrm{Cl}_{2}\) is formed with warming up

Concentrated hydrochloric acid when kept in open air sometimes produces a cloud of white fumes. The explanation for this is that (a) strong affinity of HCl gas for moisture in air results in forming of droplets of liquid solution which appears like a cloudy smoke. (b) oxygen in air reacts with the emitted HCl gas to form a cloud of chlorine gas (c) due to strong affinity for water, concen-trated hydrochloric acid pulls moisture of air towards itself. This moisture forms droplets of water and hence the cloud. (d) concentrated hydrochloric acid emits strongly smelling HCl gas all the time.

The pair of species having identical shapes for molecules of both species is (a) \(\mathrm{PF}_{\mathrm{s}}, \mathrm{IF}\), (b) \(\mathrm{XeF}_{2}, \mathrm{CO}_{2}\) (c) \(\mathrm{CF}_{4}, \mathrm{SF}\) (d) \(\mathrm{BF}_{3}, \mathrm{PCl}_{\underline{ }}\)

The soldiers of Napolean army, while at Alps during freezing winter suffered a serious problem as regards to the tin buttons of their uniforms. White metallic tin buttons got converted to grey power. This transformation is related to (a) a change in the partial pressure of oxygen in the air (b) an interaction with water vapour contained in the humid air (c) a change in the crystalline structure of tin. (d) an interaction with nitrogen of the air at very low temperatures

How is \(\mathrm{H}_{2} \mathrm{~S}\) prepared in laboratory? (a) \(\mathrm{FeS}+\mathrm{dil} \mathrm{H}_{2} \mathrm{SO}_{4}\) (b) \(\mathrm{FeSO}_{4}+\mathrm{H}_{2} \mathrm{SO}_{4}\) (c) \(\mathrm{FeS}+\) conc. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (d) elementary \(\mathrm{H}_{2}+\) elementary \(\mathrm{S}\)

Which one of the following statements regarding helium is correct? (a) it is used in gas-cooled nuclear reactors (b) it is used to produce and sustain powerful super conducting magnets (c) it is used as a cryogenic agent for carrying out experiments at low temperatures (d) all are correct

The structure of diborane \(\left(\mathrm{B}_{2} \mathrm{H}_{6}\right)\) contains \(\quad[\$ (a) four \)2 \mathrm{c}-2 \mathrm{e}\( bonds and two \)3 \mathrm{c}-2 \mathrm{e}\( bonds (b) two \)2 \mathrm{c}-2 \mathrm{e}\( bonds and four \)3 \mathrm{c}-2 \mathrm{e}\( bonds (c) two \)2 \mathrm{c}-2 \mathrm{e}\( bonds and two \)3 \mathrm{c}-3 \mathrm{e}\( bonds (d) four \)2 \mathrm{c}-2 \mathrm{e}\( bonds and four \)3 \mathrm{c}-2 \mathrm{e}$ bonds

Which of the following oxides is amphoteric in character? (a) \(\mathrm{CO}_{2}\) (b) \(\mathrm{SiO}_{2}\) (c) \(\mathrm{SnO}_{2}\) (d) \(\mathrm{CaO}\)

In silicon dioxide (a) there are double bonds between silicon and oxygen atoms (b) silicon is bonded to two silicon atoms (c) each silicon atom is surrounded by two oxygen atoms and each oxygen atom is bonded to two silicon atoms (d) each silicon atom is surrounded by four oxygen atoms and each oxygen atom is bounded to two silicon atoms

Of the following sets, which one does not contain isoelectronic species? (a) \(\mathrm{CN}^{-}, \mathrm{N}_{2}, \mathrm{C}_{2}^{2-}\) (b) \(\mathrm{PO}_{4}^{3-}, \mathrm{SO}_{4}^{2-}, \mathrm{ClO}_{4}\) (c) \(\mathrm{SO}_{3}^{2-}, \mathrm{CO}_{3}^{2-}, \mathrm{NO}_{3}\) (d) \(\mathrm{BO}_{3}^{3-}, \mathrm{CO}_{3}^{2-}, \mathrm{NO}_{3}^{3}\)

The number of hydrogen atom(s) attached to phosphorous atom in hypophosphorous acid is \(\quad\) (a) zero (b) two (c) one (d) three

The correct order of the thermal stability of hydrogen halides \((\mathrm{H}-\mathrm{X})\) is (a) \(\mathrm{HCl}>\mathrm{HF}>\mathrm{HBr}>\mathrm{HI}\) (b) \(\mathrm{HI}>\mathrm{HCl}>\mathrm{HF}>\mathrm{HBr}\) (c) \(\mathrm{HI}>\mathrm{HBr}>\mathrm{HCl}>\mathrm{HF}\) (d) \(\mathrm{HF}>\mathrm{HCl}>\mathrm{HBr}>\mathrm{HI}\)

The molecular shapes of \(\mathrm{SF}_{4}, \mathrm{CF}_{4}\), and \(\mathrm{XeF}_{4}\) are (a) different with 1,0 and 2 lone pairs of electrons on the central atoms respectively (b) different with 0,1 and 2 lone pairs of electrons on the central atoms respectively (c) the same with 1,1 and 1 lone pair of electrons on the central atoms respectively (d) the same with 2,0 and 1 lone pair of electrons on the central atoms respectively

Which of the following chemical reactions depicts the oxidizing behaviour of \(\mathrm{H}_{2} \mathrm{SO}_{4} ?\) (a) \(2 \mathrm{HI}+\mathrm{H}_{2} \mathrm{SO}_{4} \longrightarrow \mathrm{I}_{2}+\mathrm{SO}_{2}+2 \mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{Ca}(\mathrm{OH})_{2}+\mathrm{H}_{2} \mathrm{SO}_{4} \longrightarrow \mathrm{CaSO}_{4}+2 \mathrm{H}_{2} \mathrm{O}\) (c) \(\mathrm{NaCl}+\mathrm{H}_{2} \mathrm{SO}_{4} \stackrel{2}{\longrightarrow} \mathrm{NaHSO}_{4}+\mathrm{HCl}\) (d) \(2 \mathrm{PCl}_{5}+\mathrm{H}_{2} \mathrm{SO}_{4} \longrightarrow 2 \mathrm{POCl}_{3}+2 \mathrm{HCl}+\mathrm{SO}_{2} \mathrm{Cl}_{2}\)

What products are expected from the disproportionation reaction of hypochlorous acid? (a) \(\mathrm{HClO}_{3}\) and \(\mathrm{Cl}_{2} \mathrm{O}\) (b) \(\mathrm{HClO}_{2}\) and \(\mathrm{HClO}_{4}\) (c) \(\mathrm{HCl}\) and \(\mathrm{Cl}_{2} \mathrm{O}^{2}\) (d) \(\mathrm{HCl}\) and \(\mathrm{HClO}_{3}\)

Which of the following statements is true? (a) \(\mathrm{H}_{3} \mathrm{PO}_{3}\) is a stronger acid than \(\mathrm{H}_{2} \mathrm{SO}_{3}\) (b) in aqueous medium HF is a stronger acid than \(\mathrm{HCl}\) (c) \(\mathrm{HClO}_{4}\) is a weaker acid than \(\mathrm{HClO}_{3}\) (d) \(\mathrm{HNO}_{3}\) is a stronger acid than \(\mathrm{HNO}_{2}\)

Regular use of which of the following fertilizers increases the acidity of soil? (a) urea (b) super phosphate of lime (c) ammonium sulphate (d) potassium nitrate

Identify the incorrect statement among the following: (a) silicon reacts with \(\mathrm{NaOH}\) (aq) in the presence of air to give \(\mathrm{Na}_{2} \mathrm{SiO}_{3}\) and \(\mathrm{H}_{2} \mathrm{O}\) (b) \(\mathrm{Cl}_{2}\) reacts with excess of \(\mathrm{NH}_{3}\) to give \(\mathrm{N}_{2}\) and \(\mathrm{HCl}\) (c) \(\mathrm{Br}_{2}\) reacts with hot and strong \(\mathrm{NaOH}\) solution to give \(\mathrm{NaBr}, \mathrm{NaBrO}_{4}\) and \(\mathrm{H}_{2} \mathrm{O}\) (d) ozone reacts with \(\mathrm{SO}_{2}\) to give \(\mathrm{SO}_{3}\)

Which one of the following reactions of Xenon compound is not feasible? (a) \(3 \mathrm{XeF}_{4}+6 \mathrm{H}_{2} \mathrm{O} \longrightarrow 2 \mathrm{Xe}+\mathrm{XeO}_{3}+12 \mathrm{HF}+1.5 \mathrm{O}_{2}\) (b) \(2 \mathrm{XeF}_{2}+2 \mathrm{H}_{2} \mathrm{O} \longrightarrow 2 \mathrm{Xe}+4 \mathrm{HF}+\mathrm{O}_{2}\) (c) \(\mathrm{XeF}_{6}+\mathrm{RbF} \longrightarrow \mathrm{Rb}\left[\mathrm{XeF}_{7}\right]\) (d) \(\mathrm{XeO}_{3}+6 \mathrm{HF} \longrightarrow \mathrm{XeF}_{6}+3 \mathrm{H}_{2} \mathrm{O}\)

Three reactions involving \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\)are given below: (i) \(\mathrm{H}_{3} \mathrm{PO}_{4}+\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{H}_{3} \mathrm{O}^{+}+\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\) (ii) \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}+\mathrm{H}_{2} \mathrm{O} \longrightarrow \mathrm{HPO}_{4}^{2-}+\mathrm{H}_{3} \mathrm{O}^{+}\) (iii) \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}+\mathrm{OH}^{2} \longrightarrow \mathrm{H}_{3} \mathrm{PO}_{4}+\mathrm{O}^{3}\) In which of the above does \(\mathrm{H}_{2} \mathrm{PO}_{4}^{-}\)act as an acid? (a) (ii) only (b) (i) and (ii) (c) (iii) only (d) (i) only

Boron cannot form which one of the following anions? (a) \(\mathrm{BO}_{2}^{-}\) (b) \(\mathrm{BF}_{-6}^{3-}\) (c) \(\mathrm{B}(\mathrm{OH})_{4}^{-}\) (d) \(\mathrm{BH}_{4}^{-}\)

Which of the following statements regarding sulphur is incorrect? (a) At \(600^{\circ} \mathrm{C}\) the gas mainly consists of \(\mathrm{S}_{2}\) molecules. (b) The vapour at \(200^{\circ} \mathrm{C}\) consists mostly of \(\mathrm{S}_{8}\) rings. (c) \(\mathrm{S}^{2}\) molecule is paramagnetic. (d) The oxidation state of sulphur is never less than \(+4\) in its compounds.

Which of the following is the wrong statement? (a) Ozone is violet black in solid state (b) Ozone is diamagnetic gas (c) ONCl and \(\mathrm{ONO}^{-}\)are isoelectronic (d) \(\mathrm{O}_{3}\) molecule is bent