Chapter 9

Dihydrogen of high purity \((>99.95 \%)\) is obtained through: (a) the reaction of \(\mathrm{Zn}\) with dilute \(\mathrm{HCl}\). (b) the electrolysis of acidified water using Pt electrodes. (c) the electrolysis of bringe solution. (d) the electrolysis of warm \(\mathrm{Ba}(\mathrm{OH})_{2}\) solution using Ni electrodes.

The one that is NOT suitable for the removal of permanent hardness of water is : [Main Sep. 05, 2020 (II)] (a) Clark's method (b) Ion-exchange method (c) Calgon's method (d) Treatment with sodium carbonate

Hydrogen peroxide, in the pure state, is : (a) non-planar and almost colorless (b) linear and blue in color (c) linear and almost colorless (d) planar and blue in color

The equation that represents the water-gas shift reaction is: (a) \(\mathrm{CH}_{4}(\mathrm{~g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \frac{1270 \mathrm{~K}}{\mathrm{Ni}} \rightarrow \mathrm{CO}(\mathrm{g})+3 \mathrm{H}_{2}(\mathrm{~g})\) (b) \(2 \mathrm{C}(\mathrm{s})+\mathrm{O}_{2}(\mathrm{~g})+4 \mathrm{~N}_{2}(\mathrm{~g}) \stackrel{1273 \mathrm{~K}}{\longrightarrow}\) \(2 \mathrm{CO}(\mathrm{g})+4 \mathrm{~N}_{2}(\mathrm{~g})\) (c) \(\mathrm{C}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \stackrel{1270 \mathrm{~K}}{\longrightarrow} \mathrm{CO}(\mathrm{g})+\mathrm{H}_{2}(\mathrm{~g})\) (d) \(\mathrm{CO}(\mathrm{g})+\mathrm{H}_{2} \mathrm{O}(\mathrm{g}) \frac{673 \mathrm{~K}}{\text { Catalyst }} \mathrm{CO}_{2}(\mathrm{~g})+\mathrm{H}_{2}(\mathrm{~g})\)

Amongst the following, the form of water with the lowest ionic conductance at \(298 \mathrm{~K}\) is : [Main Jan. 09, 2020 (II)] (a) distilled water (b) saline water used for intravenous injection (c) water from a well (d) sea water

\(5 \mathrm{~g}\) of zinc is treated separately with an excess of (A) dilute hydrochloric acid and (B) aqueous sodium hydroxide. The ratio of the volumes of \(\mathrm{H}_{2}\) evolved in these two reactions is: (a) \(1: 2\) (b) \(1: 1\) (c) \(1: 4\) (d) \(2: 1\)

In comparison to the zeolite process for the removal of permanent hardness, the synthetic resins method is: [Main Jan. 07, 2020 (I)] (a) less efficient as it exchanges only anions (b) more efficient as it can exchange both cations as well as anions (c) less efficient as the resins cannot be regenerated (d) more efficient as it can exchange only cations

Among statements (A)-(D), the correct ones are: (A) Decomposition of hydrogen peroxide gives dioxygen. (B) Like hydrogen peroxide, compounds, such as \(\mathrm{KClO}_{3}, \mathrm{~Pb}\left(\mathrm{NO}_{3}\right)_{2}\) and \(\mathrm{NaNO}_{3}\) when heated liberate dioxygen. (C) 2-Ethylanthraquinone is useful for the industrial preparation of hydrogen peroxide. (D) Hydrogen peroxide is used for the manufacture of sodium perborate. (a) (A) (B), (C) and (D) (b) (A), (B) and (C) only (c) (A), (C) and (D) only (d) (A) and (C) only

Hydrogen has three isotopes (A), (B) and (C). If the number of neutron(s) in (A), (B) and (C) respectively, are \((x),(y)\) and \((z)\), the sum of \((x),(y)\) and \((z)\) is: (a) 3 (b) 2 (c) 4 (d) 1

The temporary hardness of a water sample is due to compound \(\mathrm{X}\). Boiling this sample converts \(\mathrm{X}\) to compound Y. \(\mathrm{X}\) and \(\mathrm{Y}\), respectively, are : [Main April 12, 2019 (II)] (a) \(\mathrm{Mg}\left(\mathrm{HCO}_{3}\right)_{2}\) and \(\mathrm{Mg}(\mathrm{OH})_{2}\) (b) \(\mathrm{Ca}\left(\mathrm{HCO}_{3}\right)_{2}\) and \(\mathrm{Ca}(\mathrm{OH})_{2}\) (c) \(\mathrm{Mg}\left(\mathrm{HCO}_{3}\right)_{2}\) and \(\mathrm{MgCO}_{3}\) (d) \(\mathrm{Ca}\left(\mathrm{HCO}_{3}\right)\), and \(\mathrm{CaO}\)

The metal that gives hydrogen gas upon treatment with both acid as well as base is : (a) magnesium (b) mercury (c) zinc (d) iron

The synonym for water gas when used in the production of methanol is: [Main April 10, 2019 (I)] (a) natural gas (b) fuel gas (c) laughing gas (d) syn gas

The volume strength of \(1 \mathrm{M} \mathrm{H}_{2} \mathrm{O}_{2}\) is : (Molar mass of \(\mathrm{H}_{2} \mathrm{O}_{2}=34 \mathrm{~g} \mathrm{~mol}^{-1}\) ) (a) \(5.6\) (b) \(16.8\) (c) \(11.35\) (d) \(22.4\)

The correct statements among (a) to (d) are : [Main April 10, 2019 (II)] (i) saline hydrides produce \(\mathrm{H}_{2}\) gas when reacted with \(\mathrm{H}_{2} \mathrm{O}\). (ii) reaction of \(\mathrm{LiAlH}_{4}\) with \(\mathrm{BF}_{3}\) leads to \(\mathrm{B}_{2} \mathrm{H}_{6}\). (iii) \(\mathrm{PH}_{3}\) and \(\mathrm{CH}_{4}\) are electron \(-\) rich and electron \(-\) precise hydrides, respectively, (iv) \(\mathrm{HF}\) and \(\mathrm{CH}_{4}\) are called as molecular hydrides. (a) (i), (ii), (iii) and (iv) (b) (iii) and (iv) only (c) (i), (iii) and (iv) only (d) (i), (ii) and (iii) only

The number of water molecules(s) not coordinated to copper ion directly in \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\), is: [Main April 9, 2019 (I)] (a) 2 (b) 3 (c) 1 (d) 4

The chemical nature of hydrogen peroxide is: (a) Oxidising agent in acidic medium, but not in basic medium. (b) Reducing agent in basic medium, but not in acidic medium. (c) Oxidising and reducing agent in acidic medium, but not in basic medium. (d) Oxidising and reducing agent in both acidic and basic medium.

\(\mathrm{NaH}\) is an example of: (a) Electron-rich hydride (b) Metallic hydride (c) Saline hydride (d) Molecular hydride

\(100 \mathrm{~mL}\) of a water sample contains \(0.81 \mathrm{~g}\) of calcium bicarbonate and \(0.73 \mathrm{~g}\) of magnesium bicarbonate. The hardness of this water sample expressed in terms of equivalents of \(\mathrm{CaCO}_{3}\) is: (molar mass of calcium bicarbonate is \(162 \mathrm{~g} \mathrm{~mol}^{-1}\) and magnesium bicarboante is \(146 \mathrm{~g} \mathrm{~mol}^{-1}\) ) [Main April 8, 2019 (I)] (a) \(5,000 \mathrm{ppm}\) (b) \(1,000 \mathrm{ppm}\) (c) \(100 \mathrm{ppm}\) (d) \(10,000 \mathrm{ppm}\)

Hydrogen peroxide oxidises \(\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4}\) to \(\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3-}\) in acidic medium but reduces \(\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{3}\) to \(\left[\mathrm{Fe}(\mathrm{CN})_{6}\right]^{4}\) in alkaline medium. The other products formed are respectively: (a) \(\left(\mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2}\right)\) and \(\mathrm{H}_{2} \mathrm{O}\) (b) \(\left(\mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2}\right)\) and \(\left(\mathrm{H}_{2} \mathrm{O}+\mathrm{OH}^{-}\right)\) (c) \(\mathrm{H}_{2} \mathrm{O}\) and \(\left(\mathrm{H}_{2} \mathrm{O}+\mathrm{O}_{2}\right)\) (d) \(\mathrm{H}_{2} \mathrm{O}\) and \(\left(\mathrm{H}_{2} \mathrm{O}+\mathrm{OH}^{-}\right)\)

The total number of isotopes of hydrogen and number of radioactive isotopes among them, respectively, are: (a) 3 and 1 (b) 3 and 2 (c) 2 and 1 (d) 2 and 0

The hardness of a water sample (in terms of equivalents of \(\mathrm{CaCO}_{3}\) ) containing \(10^{-3} \mathrm{M} \mathrm{CaSO}_{4}\) is: (molar mass of \(\mathrm{CaSO}_{4}=136 \mathrm{~g} \mathrm{~mol}^{-1}\) ) [Main Jan. 12, 2019 (I)] (a) \(10 \mathrm{ppm}\) (b) \(50 \mathrm{ppm}\) (c) \(90 \mathrm{ppm}\) (d) \(100 \mathrm{ppm}\)

From the following statements regarding \(\mathrm{H}_{2} \mathrm{O}_{2}\), choose the incorrect statement : (a) It has to be stored in plastic or wax lined glass bottles in dark (b) It has to be kept away from dust (c) It can act only as an oxidizing agent (d) It decomposes on exposure to light

The isotopes of hydrogen are: (a) Tritium and protium only (b) Protium and deuterium only (c) Protium, deuterium and tritium (d) Deuterium and tritium only

The temporary hardness of water is due to: (a) \(\mathrm{Na}_{2} \mathrm{SO}_{4}\) (b) \(\mathrm{NaCl}\) (c) \(\mathrm{Ca}\left(\mathrm{HCO}_{3}\right)_{2}\) (d) \(\mathrm{CaCl}_{2}\)

In which of the following reactions \(\mathrm{H}_{2} \mathrm{O}_{2}\) acts as a reducing agent? (i) \(\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{H}_{2} \mathrm{O}\) (ii) \(\mathrm{H}_{2} \mathrm{O}_{2}-2 \mathrm{e}^{-} \rightarrow \mathrm{O}_{2}+2 \mathrm{H}^{+}\) (iii) \(\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{e}^{-} \rightarrow 2 \mathrm{OH}^{-}\) (iv) \(\mathrm{H}_{2} \mathrm{O}_{2}+2 \mathrm{OH}^{-}-2 \mathrm{e}^{-} \rightarrow \mathrm{O}_{2}+2 \mathrm{H}_{2} \mathrm{O}\) (a) (i), (iii) (b) (ii), (iv) (c) (i), (ii) (d) (iii), (iv)

Which physical property of dihydrogen is wrong ? [Main Online April 11, 2015] (a) Odourless gas (b) Tasteless gas (c) Colourless gas (d) Non-inflammable gas

Which one of the following statements about water is FALSE? [Main 2016] (a) There is extensive intramolecular hydrogen bonding in the condensed (b) Ice formed by heavy water sinks in normal water. (c) Water is oxidized to oxygen during photosynthesis. (d) Water can act both as an acid and as a base.

Hydrogen peroxide acts both as an oxidising and as a reducing agent depending upon the nature of the reacting species. In which of the following cases \(\mathrm{H}_{2} \mathrm{O}_{2}\) acts as a reducing agent in acid medium? (a) \(\mathrm{MnO}_{4}^{-}\) (b) \(\mathrm{Cr}_{2} \mathrm{O}_{7}^{2-}\) (c) \(\mathrm{SO}_{3}^{2-}\) (d) \(\mathrm{KI}\)

Read the following statement and explanation and answer as per the options given below : Statement : The alkali metals can form ionic hydrides which contain the hydride ion \(\mathrm{H}^{-}\) Explanation : The alkali metals have low electronegativity; their hydrides conduct electricity when fused and liberate hydrogen at the anode. [ (a) Both \(\mathrm{S}\) and \(\mathrm{E}\) are true and \(\mathrm{E}\) is the correct explanation of \(\mathrm{S}\). (b) Both \(\mathrm{S}\) and \(\mathrm{E}\) are true but \(\mathrm{E}\) is not the correct explanation of \(\mathrm{S}\). (c) \(\mathrm{S}\) is true but \(\mathrm{E}\) is false. (d) \(\mathrm{S}\) is false but \(\mathrm{E}\) is true

Identify the incorrect statement regarding heavy water : [Main Online April 9, 2016] (a) It reacts with \(\mathrm{SO}_{3}\) to form deuterated sulphuric acid \(\left(\mathrm{D}_{2} \mathrm{SO}_{4}\right)\). (b) It is used as a coolant in nuclear reactors. (c) It reacts with \(\mathrm{CaC}_{2}\) to produce \(\mathrm{C}_{2} \mathrm{D}_{2}\) and \(\mathrm{Ca}(\mathrm{OD})_{2}\). (d) It reacts with \(\mathrm{Al}_{4} \mathrm{C}_{3}\) to produce \(\mathrm{CD}_{4}\) and \(\mathrm{Al}(\mathrm{OD})_{3}\).

Permanent hardness in water cannot be cured by : [Main Online April 10, 2015] (a) Treatment with washing soda (b) Boiling (c) Calgon's method (d) Ion exchange method

The numbers of protons, electrons and neutrons in a molecule of heavy water are respectively: [Main Online April 23, 2013] (a) \(8,10,11\) (b) \(10,10,10\) (c) \(10,11,10\) (d) \(11,10,10\)

The volume strength of \(8.9 \mathrm{M} \mathrm{H}_{2} \mathrm{O}_{2}\) solution calculated at \(273 \mathrm{~K}\) and 1 atm is \(.\left(\mathrm{R}=0.0821 \mathrm{~L} \mathrm{~atm} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right)\) (rounded off to the nearest integer)

To a \(25 \mathrm{~mL} \mathrm{H}_{2} \mathrm{O}_{2}\) solution, excess of acidified solution of potassium iodide was added. The iodine liberated required \(20 \mathrm{~mL}\) of \(0.3 \mathrm{~N}\) sodium thiosulphate solution. Calculate the volume strength of \(\mathrm{H}_{2} \mathrm{O}_{2}\) solution.

Heavy water is (a) \(\mathrm{H}_{2}^{18} \mathrm{O}\) (b) water obtained by repeated distillation (c) \(\mathrm{D}_{2} \mathrm{O}\) (d) water at \(4^{\circ} \mathrm{C}\)

A \(5.0 \mathrm{~cm}^{3}\) solution of \(\mathrm{H}_{2} \mathrm{O}_{2}\) liberates \(0.508 \mathrm{~g}\) of iodine from an acidified KI solution. Calculate the strength of \(\mathrm{H}_{2} \mathrm{O}_{2}\) solution in terms of volume strength at STP.

The temporary hardness of water due to calcium bicarbonate can be removed by adding - (a) \(\mathrm{CaCO}_{3}\) (b) \(\mathrm{Ca}(\mathrm{OH})_{2}\) (c) \(\mathrm{CaCl}_{2}\) (d) \(\mathrm{HCl}\)

Hydrogen peroxide acts both as an oxidising and as a reducing agent in alkaline solution towards certain first row transition metal ions. Illustrate both these properties of \(\mathrm{H}_{2} \mathrm{O}_{2}\) using chemical equations.

The hardness of a water sample containing \(10^{-3} \mathrm{M} \mathrm{MgSO}_{4}\) expressed as \(\mathrm{CaCO}_{3}\) equivalents (in ppm) is (molar mass of \(\mathrm{MgSO}_{4}\) is \(120.37 \mathrm{~g} / \mathrm{mol}\) )

Give reactions for the oxidation of hydrogen peroxide with potassium permanganate in acidic medium.

The reagent(s) used for softening the temporary hardness of water is (are) [2010] (a) \(\mathrm{Ca}_{3}\left(\mathrm{PO}_{4}\right)_{2}\) (b) \(\mathrm{Ca}(\mathrm{OH})_{2}\) (c) \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) (d) \(\mathrm{NaOCl}\)

18\. Give reasons for the following: (i) Hydrogen peroxide acts as an oxidising as well as a reducing agent. (ii) Hydrogen peroxide is a better oxidising agent that water.

The species present in solution when \(\mathrm{CO}_{2}\) is dissolved in water are \([\mathbf{2 0 0 6}-\mathbf{5 M},-1]\) (a) \(\mathrm{CO}_{2}, \mathrm{H}_{2} \mathrm{CO}_{3}, \mathrm{HCO}_{3}^{-}, \mathrm{CO}_{3}^{2-}\) (b) \(\mathrm{H}_{2} \mathrm{CO}_{3}, \mathrm{CO}_{3}^{2-}\) (c) \(\mathrm{CO}_{3}^{2-}, \mathrm{HCO}_{3}^{-}\) (d) \(\mathrm{CO}_{2}, \mathrm{H}_{2} \mathrm{CO}_{3}\)

When zeolite, which is hydrated sodium aluminium silicate, is treated with hard water the sodium ions are exchanged with [1990-1 Mark] (a) \(\mathrm{H}^{+}\)ions (b) \(\mathrm{Ca}^{++}\)ions (c) \(\mathrm{SO}_{4}^{-}\)ions (d) \(\mathrm{Mg}^{++}\)ions (e) \(\mathrm{OH}^{-}\)ions