Hydrogen — Page 8 | NEET Chemistry

Q71

Hydrogen peroxide oxidises [Fe(CN)6]4- to [Fe(CN)6]3- in acidic medium but reduces [Fe(CN)6]3- to [Fe(CN)6]4- in alkaline medium. The other products formed are, respectively :

A H2O and (H2O + OH-)

B (H2O + O2) and H2O

C (H2O + O2) and (H2O + OH-)

D H2O and (H2O + O2)

Correct Answer

Option D

Solution

In acidic medium, [Fe(CN)6]-3 is oxidise to [Fe(CN)6]-3 by H2O2.

So H2O2 will perform reduction reaction.

Reduction reaction of H2O2.

{H_2}O_2^{ - 1}\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{{\mathop{\rm Re}\nolimits} duction}} {H_2}\mathop O\limits^{ - 2}

Complete reaction : [ Fe (CN)6 ] $-$ 4 + H2O2 + 2H+

\overset{\,}\longrightarrow

2 [ Fe(CN)6 ] $-$ 3 + 2H2O In alkaline medium, [Fe (CN)6] $-$ 3 reduce to [ Fe(CN)6 ] $-$ 4 So H2O2 will oxidize.

Oxidization of H2O2 : H2

O_2^{ - 1}

\overset{\,}\longrightarrow

O_2^0

Complete reaction : [Fe (CN)6 ] $-$ 3 + H2O2 + 2OH $-$

\overset{\,}\longrightarrow

2 [Fe(CN)6 ] $-$ 4 + 2H2O + O2 So, ion acidic medium H2O and in alkaline medium O2 + H2O are produced as by product.

Q72

From the following statements regarding H2O2, choose the incorrect statement :

A It decomposes on exposure to light

B It has to be stored in plastic or wax lined glass bottles in dark

C It has to be kept away from dust

D It can act only as an oxidizing agent

Correct Answer

Option D

Solution

{H_2}{O_2}

has oxidizing and reducing properties both.

Q73

Given below are two statements: Statement-I : Methane and steam passed over a heated

\mathrm{Ni}

catalyst produces hydrogen gas. Statement-II : Sodium nitrite reacts with

\mathrm{NH}_{4} \mathrm{Cl}

to give

\mathrm{H}_{2} \mathrm{O}, \mathrm{N}_{2}

and

\mathrm{NaCl}

. In the light of the above statements, choose the most appropriate answer from the options given below :

A Statement I is correct but Statement II is incorrect

B Both the statements I and II are incorrect

C Both the statements I and II are correct

D Statement I is incorrect but Statement II is correct

Correct Answer

Option C

Solution

Let's consider each statement: Statement-I : Methane (CH₄) and steam (H₂O) can indeed react in the presence of a heated nickel catalyst to produce carbon monoxide (CO) and hydrogen gas (H₂).

This is known as the steam reforming or steam methane reforming reaction and is industrially significant for hydrogen production.

Hence, Statement-I is correct.

Statement-II : Sodium nitrite (NaNO₂) reacts with ammonium chloride (NH₄Cl) to produce nitrogen gas (N₂), water (H₂O), and sodium chloride (NaCl).

This is a standard reaction that is often used in inorganic chemistry to produce nitrogen gas.

Hence, Statement-II is also correct.

Therefore, the correct answer is Option C: Both the statements I and II are correct.

Q74

Identify the reaction which does not liberate hydrogen :

A Reaction of zinc with aqueous alkali.

B Electrolysis of acidified water using Pt electrodes.

C Allowing a solution of sodium in liquid ammonia to stand.

D Reaction of lithium hydride with B2H6.

Correct Answer

Option D

Solution

2LiH + B2H6

\overset{{Ether}}\longrightarrow

2LiBH4

Q75

The reaction of

\mathrm{H}_{2} \mathrm{O}_{2}

with potassium permanganate in acidic medium leads to the formation of mainly :

A Mn2+

B Mn4+

C Mn3+

D Mn6+

Correct Answer

Option A

Solution

The reaction of

\mathrm{KMnO}_{4}

with

\mathrm{H}_{2} \mathrm{O}_{2}

in acidic medium is as

\begin{aligned} 2 \mathrm{KMnO}_{4}+3 \mathrm{H}_{2} \mathrm{SO}_{4}+5 \mathrm{H}_{2} \mathrm{O}_{2} \\ & \rightarrow \mathrm{K}_{2} \mathrm{SO}_{4}+2 \mathrm{MnSO}_{4}+8 \mathrm{H}_{2} \mathrm{O}+5 \mathrm{O}_{2} \end{aligned}

\therefore \mathrm{Mn}^{2+}

will be formed as the product.

Q76

In basic medium, H2O2 exhibits which of the following reactions? (A) Mn2+

\to

Mn4+ (B) I2

\to

I

-

(C) PbS

\to

PbSO4 Choose the most appropriate answer from the options given below :

A (B) only

B (A), (B) only

C (A) only

D (A), (C) only

Correct Answer

Option B

Solution

In basic medium, oxidising action of H2O2.

Mn2+ + H2O2 $\to$ Mn+4 + 2OH– In basic medium, reducing action of H2O2.

I2 + H2O2 + 2OH– $\to$ 2I– + 2H2O + O2 In acidic medium, oxidising action of H2O2.

PbS(s) + 4H2O2(aq) $\to$ PbSO4(s) + 4H2O(l)

Q77

The equation that represents the water-gas shift reaction is :

A CO(g) + H2O(g)

\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{Catalyst}^{673K}}

CO2(g) + H2(g)

B CH4(g) + H2O(g)

\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{Ni}^{1270K}}

CO(g) + 3H2(g)

C C(s) + H2O(g)

\overset{{1270K}}\longrightarrow

CO(g) + H2(g)

D 2C(s) + O2(g) + 4N2(g)

\overset{{1273K}}\longrightarrow

2CO(g) + 4N2(g)

Correct Answer

Option A

Solution

(A) Water gas shift reaction CO(g) + H2O(g)

\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{Catalyst}^{673K}}

CO2(g) + H2(g) (B) Water gas is produced by this reaction CH4(g) + H2O(g)

\mathrel{\mathop{\kern0pt\longrightarrow} \limits_{Ni}^{1270K}}

CO(g) + 3H2(g) (C) Water gas is produced by this reaction C(s) + H2O(g)

\overset{{1270K}}\longrightarrow

CO(g) + H2(g) (D) Producer gas is produced by this reaction 2C(s) + O2(g) + 4N2(g)

\overset{{1273K}}\longrightarrow

2CO(g) + 4N2(g)

Q78

Deuterium resembles hydrogen in properties but :

A reacts slower than hydrogen

B reacts vigorously than hydrogen

C reacts just as hydrogen

D emits

\beta

+ particles

Correct Answer

Option A

Solution

The bond dissociation energy of D2 is greater than H2 and therefore D2 reacts slower than H2.

Q79

The oxide that gives H2O2 most readily on treatment with H2O is :

A PbO2

B Na2O2

C SnO2

D BaO2 . 8H2O

Correct Answer

Option B

Solution

(a) PbO2 + 2H2O $\to$ Pb(OH)4 (b) Na2O2 + 2H2O $\to$ 2NaOH + H2O2 this reaction is possible at room temperature (c) SnO2 + 2H2O $\to$ Sn(OH)4 (d) Acidified BaO2 .

8H2O gives H2O2 after evaporation.

Q80

NaH is an example of :

A metallic hydride

B saline hydride

C electron-rich hydrid

D molecular hydride

Correct Answer

Option B

Solution

NaH is an example of ionic hydride which is also known as saline hydride.