Chemistry Test-37

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Chemistry Test-37

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Weekly Quiz Competition

Question 1
4 / -1

Which of the following statements regarding photochemical smog is not correct?

A
Carbon monoxide does not play any role in photochemical smog formation.

B
Photochemical smog is an oxidizing agent in character.

C
Photochemical smog is formed through photochemical reaction involving solar energy.

D
Photochemical smog does not cause irritation in eyes and throat.

Solution

Photochemical smog occurs in warm, dry and sunny climate. The main components of the photochemical smog result from the action of sunlight on unsaturated hydrocarbons and nitrogen oxides produced by automobiles and factories. Photochemical smog has high concentration of oxidising agents and is, therefore, called as oxidising smog. The common components of photochemical smog are ozone, nitric oxide, acrolein, formaldehyde and peroxyacetyl nitrate (PAN). Photochemical smog causes serious health problems. Both ozone and PAN act as powerful eye irritants. Ozone and nitric oxide irritate the nose and throat and their high concentration causes headache, chest pain, dryness of the throat, cough and difficulty in breathing. Photochemical smog leads to cracking of rubber and extensive damage to plant life. It also causes corrosion of metals, stones, building materials, rubber and painted surfaces.
Question 2
4 / -1

The vapour pressure of two pure liquids A and B are 100 and 80 torr respectively. The total vapour pressure of solution obtained by mixing 2 moles of A and 3 moles of B would be:

A
120 torr

B
36 torr

C
88 torr

D
180 torr

Solution

Total vapour pressure \(\mathrm{P}=\mathrm{P}_{\mathrm{A}}+\mathrm{P}_{\mathrm{B}}\)
\(\mathrm{P}_{\mathrm{A}}=100 \times \frac{2}{2+3}=100 \times \frac{2}{5}=40\) torr
\(\mathrm{P}_{\mathrm{B}}=80 \times \frac{3}{2+3}=80 \times \frac{3}{5}=48\) torr
\(\mathrm{P}_{\text {Total }}=\mathrm{P}_{\mathrm{A}}+\mathrm{P}_{\mathrm{B}}=40+48=88\) torr
Question 3
4 / -1

\(28\) g \(N _{2}\) and \(6.0\)g of \(H _{2}\) are heated over catalyst in a closed one litre flask of \(450^{\circ} C\). The entire equilibrium mixture required \(500 mL\) of \(1.0 M\) \(H _{2} SO _{4}\) for neutralisation. The value of \(K _{ c }\) for the reaction
\(N _{2}( g )+3 H _{2}( g ) \rightleftharpoons 2 NH _{3}( g )\) is

A
\(1.69 mol ^{2} L ^{2-}\)

B
\(0.05 mol ^{2} L ^{2-}\)

C
\(0.59 mol ^{2} L ^{2-}\)

D
\(0.06 mol ^{2} L ^{2-}\)

Solution

Moles of \(N _{2}=\frac{28}{28}=1\),
Moles of \(H _{2}=\frac{6}{2}=3\)
Moles of \(H _{2} SO _{4}\) required \(=\frac{500 \times 1}{1000}=0.5\)
Moles of \(NH _{3}\) neutralised by \(H _{2} SO _{4}=1.0\)
\(\left(2 NH _{3}+ H _{2} SO _{4} \longrightarrow\left( NH _{4}\right)_{2} SO _{4}\right)\)
So \(1\) mol of \(NH _{3}\) by the reaction between \(N _{2}\) and \(H _{2}\).
\(\quad \quad \quad \quad \quad \quad N _{2}+3 H _{2} \rightleftharpoons 2 NH _{3}\)
initial \( \quad \quad\quad\quad 1 \quad \quad 3 \quad \quad \quad 0 \)
at eqm \(\quad (1-0.5) ( 3-0.5 \times 3) \quad 1\)
\(K _{ c }=\frac{1 \times 1}{0.5 \times(1.5)^{3}}=0.59 mol ^{2} L ^{2-}\)
Question 4
4 / -1

For the feasibility of a redox reaction in a cell, the emf should be:

A
Positive

B
Fixed

C
Zero

D
Negative

Solution

Any redox reaction would occur spontaneously if the free energy charge, \((\Delta G)\) is negative.
Relation between \(\triangle G\) and \(E_{\text {cell }}\) is
\(-\Delta G=n F E_{\text {cell }}\)
At standard conditions,
\(\Delta G^{\circ}=n F E_{\text {cell }}^0\)
where,
\(n\) is the number of electrons involved in the reaction.
\(F\) is the Faraday constant
\(E^0\) is the cell emf
If \(\Delta G^0\) is negative, then the \(E^0\) value will be positive.
Thus, for a feasible redox reaction, the emf of the cell should be positive.
Question 5
4 / -1

A radioactive material of half-life \(T\) was produced in a nuclear reactor at different instants, the quantity produced second time was twice of that produced first time. If now their present activities are \(A _{1}\) and \(A _{2}\) respectively then their age difference equals:

A
\(\frac{ T }{ln 2}\left| ln \frac{ A _{1}}{ A _{2}}\right|\)

B
\(T \left| ln \frac{ A _{1}}{ A _{2}}\right|\)

C
\(\frac{T}{ ln 2}\left| ln \frac{A_{2}}{2 A_{1}}\right|\)

D
\(T \left | ln \frac{ A _{2}}{2 A _{1}}\right|\)

Solution

Given,
\(N _{1}= N _{0}, N _{2}=2 N _{0}\)
\(t _{1}=\frac{1}{\lambda} ln \frac{\lambda N _{0}}{ A _{1}}\)
\(t _{2}=\frac{1}{\lambda} ln \frac{\lambda 2 N _{0}}{ A _{2}}\)
So, \(t _{2}- t _{1}=\frac{1}{\lambda} ln \frac{ A _{2}}{2 A _{1}}\)
Using \(T =\frac{ln 2}{\lambda}\)
\(t _{2}- t _{1}=\left|\frac{ T }{ln 2} ln \frac{ A _{2}}{2 A _{1}}\right|\)
Question 6
4 / -1

Oxidation state of \(\mathrm{N}\) in \(\mathrm{NO}_{4}^{+}\) is:

A
+4

B
-8

C
-6

D
+9

Solution

Let the oxidation state of \(\mathrm{N}\) be \(\mathrm{x}\).
\(\therefore \mathrm{x}+4 \times(-2)=+1 \)
\(\Rightarrow \mathrm{x}-8=+1 \)
\(\Rightarrow \mathrm{x}=+9\)
Therefore, oxidation state of \(\mathrm{N}\) in \(\mathrm{NO}_{4}^{+}\)is \(+9\).
Question 7
4 / -1

Metals are refined by using different methods. Which of the following metals are refined by electrolytic refining?
(i) Au
(ii) Cu
(iii) Na
(iv) K

A
(i) and (ii)

B
(i) and (iii)

C
(ii) and (iii)

D
(iii)and (iv)

Solution

Electrolytic refining is used for metals like Cu, Zn, Ag, Au etc. The method to be used for refining an impure metal depends on the nature of the metals well as on the nature of impurities present in it. So, metals Au (gold) and Cu (copper) are refined by electrolytic refining.
Question 8
4 / -1

An increase in the concentration of the reactantsof a reaction leads to change in:

A
Activation energy

B
Heat of reaction

C
Threshold energy

D
Collision frequency

Solution

The number of collisions that takes place per second per unit volume of the reaction mixture is known as collision frequency \(\mathrm Z\).
As the concentration of reactants increases the number of reactant molecules per unit volume increases which increases the collision frequency.
\(Z \propto\) number of reactant molecules per unit volume
Question 9
4 / -1

Lindane can be obtained by the reaction of benzene with:

A
CH₂Cl/anhydrous AlCl₃

B
C₂H₄I/anhydrous AlCl₃

C
CH₃COCl/anhydrous AlCl₃

D
Cl₂in sunlight

Solution

Lindane is γ -benzene hexachloride. It can be prepared by benzene with Cl₂ in sunlight.

Question 10

4 / -1

Which of the following is the atomic number of an element that forms basic oxide?

\(20\)

\(18\)

\(15\)

\(17\)

Solution

\(20\)is the atomic number of an element that forms basic oxide.

Metals form basic oxide while non-metals can form acidic oxides.Generally, metals can have \(1\) to \(3\) electrons in their outermost shell and non-metals have \(4\) to \(8\) electrons in the outermost shell.The electronic configuration of given elements are:

Atomic Number	Configuration
\(7\) (Nitrogen)	\(2, 5\)
\(20\) (Calcium)	\(2, 8, 8, 2\)
\(17\) (Chlorine)	\(2, 8, 7\)
\(6\) (Carbon)	\(2, 4\)

So element with atomic number \(20\) (Calcium) having configuration \(2, 8, 8, 2\) is metal and it will form a basic oxide.

Rest three elements having atomic numbers, \(7, 17\) and \(6\) are non-metals and hence they form acidic oxides.

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Chemistry Test-37

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Question 1

Carbon monoxide does not play any role in photochemical smog formation.

Photochemical smog is an oxidizing agent in character.

Photochemical smog is formed through photochemical reaction involving solar energy.

Photochemical smog does not cause irritation in eyes and throat.

Solution

Question 2

120 torr

36 torr

88 torr

180 torr

Solution

Question 3

\(1.69 mol ^{2} L ^{2-}\)

\(0.05 mol ^{2} L ^{2-}\)

\(0.59 mol ^{2} L ^{2-}\)

\(0.06 mol ^{2} L ^{2-}\)

Solution

Question 4

Positive

Fixed

Zero

Negative

Solution

Question 5

\(\frac{ T }{ln 2}\left| ln \frac{ A _{1}}{ A _{2}}\right|\)

\(T \left| ln \frac{ A _{1}}{ A _{2}}\right|\)

\(\frac{T}{ ln 2}\left| ln \frac{A_{2}}{2 A_{1}}\right|\)

\(T \left | ln \frac{ A _{2}}{2 A _{1}}\right|\)

Solution

Question 6

+4

-8

-6

+9

Solution

Question 7

(i) and (ii)

(i) and (iii)

(ii) and (iii)

(iii)and (iv)

Solution

Question 8

Activation energy

Heat of reaction

Threshold energy

Collision frequency

Solution

Question 9

CH2Cl/anhydrous AlCl3

C2H4I/anhydrous AlCl3

CH3COCl/anhydrous AlCl3

Cl2 in sunlight

Solution

Question 10

\(20\)

\(18\)

\(15\)

\(17\)

Solution

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CH₂Cl/anhydrous AlCl₃

C₂H₄I/anhydrous AlCl₃

CH₃COCl/anhydrous AlCl₃

Cl₂in sunlight