Hydrogen — Page 2 | JEE Chemistry

Q11

In context with the industrial preparation of hydrogen from water gas (CO + H2), which of the following is the correct statement?

A CO and H2 are fractionally separated using differences in their densities

B CO is removed by absorption in aqueous Cu2Cl2 solution

C H2 is removed through occlusion with Pd

D CO is oxidised to CO2 with steam in the presence of a catalyst followed by absorption of CO2 in alkali

Correct Answer

Option D

Solution

On the industrial scale hydrogen is prepared from water gas according to following reaction sequence

\underbrace {CO + {H_2}}_{water\,\,\,gas} + \underbrace {{H_2}O}_{\left( {steam} \right)}\,\,\overset{{catalyst}}\longrightarrow C{O_2} + 2{H_2}

\,\,\,\,\,\,\,\,\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{\left( {alkali} \right)}^{2NaOH}} N{a_2}C{O_3} + {H_2}O

From the above it is clear that

CO

is first oxidised to

C{O_2}

which is then ansorbed in

NaOH.

Q12

Very pure hydrogen (99.9%) can be made by which of the following processes?

A Reaction of methane with steam

B Mixing natural hydrocarbons of high molecular weight

C Electrolysis of water

D Reaction of salt like hydrides with water

Correct Answer

Option D

Solution

Very pure hydrogen (99.9%) can be prepared by the action of water on any hydrides i.e, sodium hydride(NaH), Calcium Hydride(CaH2) etc.

NaH + {H_2}O \to NaOH + {H_2}

(very pure Hydrogen) By electrolysis of water we get 99.5% pure hydrogen. 2H2O

\overset{{Electrolysis}}\longrightarrow

2H2 + O2 Note : By electrolysis of water we can't get 99.9% pure hydrogen we only get around 99.5% pure hydrogen.

That is why option (C) is wrong.

Q13

The metal that gives hydrogen gas upon treatment with both acid as well as base is :

A mercury

B zinc

C iron

D magnesium

Correct Answer

Option B

Solution

Zn + 2HCl $\to$ ZnCl2 + H2 Zn + NaOH $\to$ Na2ZnO2 + H2 Here zinc(Zn) is amphoteric metal, that is why it reacts with both acid and base.

Q14

100 mL of a water sample contains 0.81 g of calcium bicrabonate and 0.73 g of magnesium bicarbonate. The hardness of this water sample expressed in terms of equivalents of CaCO3 is : (Molar mass of calcium bicarbonate is 162 g mol–1 and magnesium bicarbonate is 146 g mol–1)

A 1,000 ppm

B 100 ppm

C 10,000 ppm

D 5,000 ppm

Correct Answer

Option C

Solution

Here hardness of water is expressed in terms of CaCO3.

$\therefore$ Equivalent of CaCO3 = Equivalent of Ca(HCO3)2 + Equivalent of Mg(HCO3)2 $\Rightarrow$ 2 $\times$

{W \over {100}}

=

{{0.81} \over {162}} \times 2 + {{0.73} \over {146}} \times 2

$\Rightarrow$ W = 1 gm Volume of water = 100 mL $\therefore$ Mass of water = 100 g $\therefore$ Hardness =

{{1.0} \over {100}} \times {10^6}

= 10000 ppm

Q15

The temporary hardness of water is due to :

A Na2SO4

B NaCl

C Ca(HCO3)2

D CaCl2

Correct Answer

Option C

Solution

Ca(HCO3)2 is responsible for temporary hardness of water.

Q16

The one that is NOT suitable for the removal of permanent hardness of water is :

A Ion-exchange method

B Calgon's method

C Treatment with sodium carbonate

D Clark's method

Correct Answer

Option D

Solution

For Removal of Temporary hardness two methods are present (1) Clark’s method (2) Boiling While permanent hardness of water can be removed 4 methods (1) Washong soda method (Na2CO3 method), (2) Calgon method (3) Permutit Process (4) Ion-exchange Resin method.

Q17

Dihydrogen of high purity (> 99.95%) is obtained through :

A the electrolysis of acidified water using Pt electrodes

B the electrolysis of warm Ba(OH)2 solution using Ni electrodes

C the electrolysis of brine solution

D the reaction of Zn with dilute HCl

Correct Answer

Option B

Solution

To obtain H2 of high purity (> 99.95 %) electrolysis of Ba(OH)2 solution is done using Ni electrodes.

Q18

Hydrogen peroxide, in the pure state, is :

A Linear and blue in color

B Linear and almost colorless

C Non-planar and almost colorless

D Planar and bluein color

Correct Answer

Option C

Solution

Hydrogen peroxide, in the pure state, has openbook like structure which is non- planar and almost colourless (very pale blue) liquid.

Q19

Amongst the following, the form of water with the lowest ionic conductance at 298 K is :

A saline water used for intravenous injection

B sea water

C distilled water

D water from a well

Correct Answer

Option C

Solution

The form of H2O with the lowest ionic conductance at 298 K is distilled water.

Q20

Among the statements (a) - (d), the correct ones are : (a) Decomposition of hydrogen peroxide gives dioxygen. (b) Like hydrogen peroxide, compounds, such as KCIO3, Pb(NO3)2 and NaNO3 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) and (c) only

C (a), (b) and (c) only

D (a), (c) and (d) only

Correct Answer

Option A

Solution

H2O2

\overset{\Delta}\longrightarrow

2H2O +O2 KClO3, Pb(NO3)2, NaNO3 on heating will release O2 gas. 2H3BO3 + 2NaOH + 2H2O2 $\to$ Na2[B2(O2)(OH)4] + 4H2O