Hydrogen — Page 6 | JEE Chemistry

Q51

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R Assertion A : Hydrogen is an environment friendly fuel. Reason R : Atomic number of hydrogen is 1 and it is a very light element. In the light of the above statements, choose the correct answer from the options given below :

A Both A and R are true but R is NOT the correct explanation of A

B A is false but R is true

C A is true but R is false

D Both A and R are true and R is the correct explanation of A

Correct Answer

Option A

Solution

The correct answer is (A) Both A and R are true but R is NOT the correct explanation of A.

Assertion A is true that hydrogen is an environmentally friendly fuel because when hydrogen is combusted it produces only water vapor and no harmful pollutants or greenhouse gases.

Reason R is also true that the atomic number of hydrogen is 1 and it is a very light element.

However, it is not a correct explanation for Assertion A as the environmental friendliness of hydrogen as a fuel is not solely determined by its atomic number or weight, but rather by how it is produced, stored, and transported.

The environmental impact of hydrogen as a fuel source depends on various factors, such as the method used for its production and the emissions associated with its transportation and storage.

Q52

The products obtained from a reaction of hydrogen peroxide and acidified potassium permanganate are :

A

\mathrm{Mn}^{4+}, \mathrm{H}_{2} \mathrm{O}

only

B

\mathrm{Mn}^{2+}, \mathrm{H}_{2} \mathrm{O}

only

C

\mathrm{Mn}^{4+}, \mathrm{H}_{2} \mathrm{O}, \mathrm{O}_{2}

only

D

\mathrm{Mn}^{2+}, \mathrm{H}_{2} \mathrm{O}, \mathrm{O}_{2}

only

Correct Answer

Option D

Solution

2 \mathrm{MnO}_{4}^{-}+6 \mathrm{H}^{+}+5 \mathrm{H}_{2} \mathrm{O}_{2} \longrightarrow 2 \mathrm{Mn}^{2+}+8 \mathrm{H}_{2} \mathrm{O}+5 \mathrm{O}_{2}

This reaction shows reducing action of

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

in acidic medium. The products formed are

\mathrm{Mn}^{2+}, \mathrm{H}_{2} \mathrm{O}

and

\mathrm{O}_{2}

Q53

Which one of the following methods is most suitable for preparing deionized water?

A Synthetic resin method

B Clark's method

C Calgon's method

D Permutit method

Correct Answer

Option A

Solution

Pure demineralised (de-ionized) water free from all soluble mineral salts is obtained by passing water successively through a cation exchange (in the H+ form) and an anion exchange (in the OH $-$ form) resins.

Q54

Hydrogen has three isotopes : protium (1H), deuterium (2H or D) and tritium (3H or T). They have nearly same chemical properties but different physical properties. They differ in :

A number of protons.

B atomic number.

C electronic configuration.

D atomic mass.

Correct Answer

Option D

Solution

1H, 2H and 3H have same atomic number but their atomic masses are different.

Isotopes have same atomic number (i.e. same number of protons)

Q55

High purity (> 99.95%) dihydrogen is obtained by :

A reaction of zinc with aqueous alkali.

B electrolysis of acidified water using platinum electrodes.

C electrolysis of warm aqueous barium hydroxide solution between nickel electrodes.

D reaction of zinc with dilute acid.

Correct Answer

Option C

Solution

High purity (>99.95 %)

\mathrm{H}_{2}

is obtained by electrolysing warm aqueous

\mathrm{Ba}(\mathrm{OH})_{2}

solution between nickel electrodes.

Q56

(A) HOCI + H2O2 → H3O+ + Cl- + O2 (B) I2 + H2O2 + 2OH- → 2I- + 2H2O + O2 Choose the correct option.

A H2O2 acts as reducing and oxidising agent respectively in equations (A) and (B).

B H2O2 act as oxidizing and reducing agent respectively in equations (A) and (B).

C H2O2 acts as oxidising agent in equations (A) and (B).

D H2O2 acts as reducing agent in equations (A) and (B).

Correct Answer

Option D

Solution

In equation (A), HOCl undergoes reduction in presence of H2O2.

Here, oxidation state of Cl changes from +1 to –1 (i.e. reduces) $\therefore$ H2O2 act as reducing agent I2 reduces to I- in presence of H2O2.

In equation (B), Here oxidation state of iodine decreases (from 0 to –1) $\therefore$ H2O2 act as reducing agent in both the equations.

Q57

The products obtained during treatment of hard water using Clark's method are :

A

\mathrm{CaCO}_{3}

and

\mathrm{MgCO}_{3}

B

\mathrm{Ca}(\mathrm{OH})_{2}

and

\mathrm{Mg}(\mathrm{OH})_{2}

C

\mathrm{CaCO}_{3}

and

\mathrm{Mg}(\mathrm{OH})_{2}

D

\mathrm{Ca}(\mathrm{OH})_{2}

and

\mathrm{MgCO}_{3}

Correct Answer

Option C

Solution

In Clark's method lime water is used

\begin{aligned} &\mathrm{Ca}\left(\mathrm{HCO}_3\right)_2+2 \mathrm{Ca}(\mathrm{OH})_2 \rightarrow 2 \mathrm{CaCO}_3+2 \mathrm{H}_2 \mathrm{O} \\\\ &\mathrm{Mg}\left(\mathrm{HCO}_3\right)_2+2 \mathrm{Ca}(\mathrm{OH})_2 \rightarrow 2 \mathrm{CaCO}_3+\mathrm{Mg}(\mathrm{OH})_2+2 \mathrm{H}_2 \mathrm{O} \end{aligned}

Q58

Dihydrogen reacts with CuO to give :

A CuH2

B Cu

C Cu2O

D Cu(OH)2

Correct Answer

Option B

Solution

CuO + H2 $\to$ Cu + H2O (under hot conditions)

Q59

The correct statements among (a) to (d) regarding H2 as a fuel are : (a) It produces less pollutants than petrol. (b) A cylinder of compressed dihydrogen weighs

\sim

30 times more than a petrol tank producing the same amount of energy. (c) Dihydrogen is stored in tanks of metal alloys like NaNi5. (d) On combustion, values of energy released per gram of liquid dihydrogen and LPG are 50 and 142 KJ, respectively.

A (a) and (c) only

B (b) and (d) only

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

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

Correct Answer

Option C

Solution

(I) H2 is a 100% pollution free fuel. So, option (I) is correct. (II) Molecular weight of H2(2u).

= {1 \over {29}} \times

molecular weight of butane, C4H10 (LPG) [58u].

So, compressed H2 weighs $\sim$ 30 times more than a petrol tank and option (b) is correct.

(III) NaNi5, Ti - TiH2 etc. are used for storage of H2 in small quantities.

Thus, option (c) is correct.

(IV) On combustion values of energy released per gram of liquid dihydrogen (H2) : 142 kJ g $-$ 1, and for LPG : 50 kJ g $-$ 1.

So, option (d) is incorrect.

Q60

The functional groups that are responsible for the ion-exchange property of cation and anion exchange resins, respectively, are :

A

-

SO3H and

-

NH2

B

-

NH2 and COOH

C

-

NH2 and

-

SO3H

D

-

SO3H and

-

COOH

Correct Answer

Option A

Solution

Cation exchange resins contain large organic a molecule with –SO3H group.

In the cation exchange process H+ exchanges for Na+, Ca2+, Mg2+ and other cations present in water.

While anion exchange resins contain –NH2 in form of –NH3+ OH– where OH– exchanges for anions like Cl–, HCO3–, SO4 2–, etc.