Tag: chemical reactions

Quizzes (8) Questions (144)

Questions Related to chemical reactions

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

A current being passed for two hour through a solution of an acid liberating 11.2 litre of oxygen at NTP at anode. What will be the amount of copper deposited at the cathode by the same current when passed through a solution of copper sulphate for the same time?

  1. 16 g

  2. 63 g

  3. 31.5 g

  4. 8 g
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Solution:- (B) $63 \; g$

At STP,
$1$ mole of oxygen gas $= 32 \; g = 22.4 \; L$
Therefore,
$11.2 \; L$ of ${O} _{2} = \cfrac{32}{22.4} \times 11.2 = 16 \; g$
Therefore,
$\cfrac{{M} _{Cu}}{{M} _{{O} _{2}}} = \cfrac{{E} _{Cu}}{{E} _{O}}$
$\Rightarrow \cfrac{{M} _{Cu}}{16} = \cfrac{\left( \cfrac{63}{2} \right)}{\left( \cfrac{16}{2} \right)}$
$\Rightarrow {M} _{Cu} = 63 \; g$
Hence the amount of copper deposited at the cathode is $63 \; g$.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

A current of 9.65 Ampere flowing for 10 minutes deposits 3 g of metal which is monovalent, the atomic mass of metal is a:

  1. 10

  2. 50

  3. 30

  4. 96.5
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Solution:- (B) $50$

Weight of metal deposited $= 3 \; g$
Quantity of electricity passed $\left( q \right)$-
$q = I \times t$
Given:-
$I = 9.65 A$
$t = 10 \; min = 10 \times 60 = 600 \; sec$
$\therefore q = 9.65 \times 600 = 5790 \; C$
Now, as we know that,
Eq. wt. of metal $= \cfrac{\text{Weight of metal}}{q} \times F$
$\Rightarrow$ Eq. wt. of metal $= \cfrac{3}{5790} \times 96500 = 50 \; g$
As the metal is monovalent, atomic weight of metal will be equal to its equivalent weight.
Therefore,
Atomic weight of metal $= 50 \; g$

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

Which of the following ($1\ M$) conducts more electricity?

  1. Sulphuric acid

  2. Boric acid

  3. Nitric acid

  4. Phosphorous acid
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Conductivity in solutions depends on the degree of dissociation. Sulfuric acid (H2SO4) is a strong acid and dissociates completely into ions, whereas boric and phosphorous acids are weak acids and dissociate poorly.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

The charge required to deposit 40.5 g of Al(atomic mass=27.0 g) from the fused ${ Al } _{ 2 }{ \left( { SO } _{ 4 } \right) } _{ 3 }$ is :

  1. $4.34\times { 10 }^{ 5 }C$
  2. $43.4\times { 10 }^{ 5 }C$
  3. $1.44\times { 10 }^{ 5 }C$

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The reaction is Al^3+ + 3e- -> Al. 1 mole of Al (27g) requires 3 Faradays (3 * 96500 C). For 40.5g, the moles of Al = 40.5 / 27 = 1.5 moles. Charge = 1.5 * 3 * 96500 = 4.5 * 96500 = 434250 C, which is 4.34 * 10^5 C.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

Electrolytic conductivity of $0.3 M$ solution of $KCI$ at $298 K $is $3.72$ x ${10}^{-2}Scm^{-1}$.Calculate its molar conductivity ($S cm^{2} mol ^{-1}$) 

  1. $124$
  2. $30.56$
  3. $192$
  4. $185$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Given,

$k=3.72\times 10^{-2}\ Scm^{-1}$
$c=0.3M$

Molar conductivity($m$) is given by,

$m=\dfrac{k\times 1000}{c}$

$\Rightarrow m=\dfrac{3.72\times 10^{-2}\times 1000}{0.3}$

$\Rightarrow m=124\ S\ cm^2mol^{-1}$

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

Resistance of decimolar solution is 50 ohm. If electrodes of surface area 0.0004 $m^2$ each are placed at a distance of 0.02 m then conductivity of solution is : 

  1. $1 \,s\,cm^{-1}$
  2. $0.01 \,s\,cm^{-1}$
  3. $0.001 \,s\,cm^{-1}$
  4. $10 \,s\,cm^{-1}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Conductivity k = (1 / R) * (l / A). Resistance R = 50 ohm, distance l = 0.02 m = 2 cm, area A = 0.0004 m^2 = 4 cm^2. Thus k = (1 / 50) * (2 / 4) = 0.02 * 0.5 = 0.01 S cm^-1.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

Which statement is not correct ?

  1. Conductance of an electrolytic solution increase with dilution

  2. Conductance of an electrolytic solution decrease with dilution

  3. specific conductance of an electrolytic solution decrease with dilution

  4. Equivalent conductance of an electrolytic solution increase with dilution
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Specific conductance (kappa) decreases with dilution because the number of ions per unit volume decreases. Conductance and equivalent conductance increase with dilution because the total number of ions or the mobility of ions increases.

Multiple choice metallic and electrolytic conduction electrolysis chemical reactions electrochemistry chemistry

Molten potassium chloride conducts electricity due to the presence of  _______ .

  1. free electron

  2. free ions

  3. free molecules

  4. atom of potassium & chloride
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Ionic compounds like potassium chloride (KCl) conduct electricity in the molten state because the crystal lattice breaks down, allowing the K+ and Cl- ions to move freely.