Chemistry Test

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Chemistry Test - 13

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Weekly Quiz Competition

Question 1
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Iron carbonyl, \(\mathrm{Fe}(\mathrm{CO})_{5}\) is

A
Trinuclear

B
Mononuclear

C
Tetranuclear

D
Dinuclear

Solution

Iron carbonyl, \(\mathrm{Fe}(\mathrm{CO})_{5}\) is mononuclear. \(\operatorname{In~} \mathrm{Fe}(\mathrm{CO})_{5}\), one \(\mathrm{Fe}\) atom is surrounded by 5 CO ligands. Mononuclear complexes are those complex which one metal atom/ion is surrounded by ligands.
Question 2
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Two solutions of a substance are mixed in the following manner: \(480 ~mL\) of \(1.5~ M\) first solution \(+520 ~mL\) of \(1.2 ~M\) second solution. What is the molarity of the final mixture?

A
\(1.20~ M\)

B
\(1.50 ~M\)

C
\(1.344~ M\)

D
\(2.70~ M\)

Solution

\(M _{ net }=\frac{ M _{1} V _{1}+ M _{2} V _{2}}{ V _{1}+ V _{2}}\)
Total millimoles of solute\((M _{1} V _{1}+ M _{2} V _{2})=480 \times 1.5+520 \times 1.2\)
\(=720+624=1344\)
Total volume \( (V _{1}+ V _{2})=480+520=1000\)
Molarity of the final mixture \(=\frac{1344 }{1000}\)
\(=1.344 ~M\)
Question 3
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Identify compound X in the following sequence of reactions:

A

B

C

D

Solution

In the first step free radical chlorination takes place and in the second step after hydrolysis the stable product benzaldehyde is formed.
Question 4
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Specific conductance of \(0.1 \mathrm{ {M} {~NaCl}}\) solution is \(1.01 \times 10^{-2} \mathrm{{ohm}^{-1} {~cm}^{-1}}\). Its molar conductance in \(\mathrm{ohm ^{-1} {~cm}^{2} {~mol}^{-1}}\) is:

A
\(1.01 \times 10^{-2} \mathrm{{ohm}^{-1} {~cm}^{2} {~mol}^{-1}}\)

B
\(1.01 \times 10^{3} \mathrm{{ohm}^{-1} {~cm}^{2} {~mol}^{-1}}\)

C
\(1.01 \times 10^{2} \mathrm{{ohm}^{-1} {~cm}^{2} {~mol}^{-1}}\)

D
\(1.01 \times 10^{-3} \mathrm{{ohm}^{-1} {~cm}^{2} {~mol}^{-1}}\)

Solution

Molar conductivity is defined as the conductivity of an electrolyte solution divided by the molar concentration of electrolyte.
Given,
Specific Conductance, \((\kappa)=1.01 \times 10^{-2} {ohm}^{-1} {~cm}^{-1}\)
Molarity, \((M)=0.1 M\)
We know the relation,
\(\Lambda_{m}=\frac{\kappa \times 1000}{M}\)
\(=\frac{1.01 \times 10^{-2} \times 1000}{0.1}\)
\(=1.01 \times 10^{-2} \mathrm{{ohm}^{-1} {~cm}^{2} {~mol}^{-1}}\)
Question 5
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The product(s) formed when \(H _{2} O _{2}\) reacts with disodium hydrogen phosphate is:

A
\(P _{2} O _{5} \cdot Na _{3} P O _{4}\)

B
\(Na _{2} HP O _{4} \cdot H _{2} O _{2}\)

C
\(NaH _{2} P O _{4}, H _{2} O\)

D
\(Na _{2} HPO _{4} \cdot H _{2} O\)

Solution

The product(s) formed when \(H _{2} O _{2}\) reacts with disodium hydrogen phosphate is \(Na _{2} HP O _{4} \cdot H _{2} O _{2}\).
\(H _{2} O _{2}+ Na _{2} HP O _{2} \rightarrow \underset{\text{addition product}}{Na _{2} HP O _{4} \cdot H _{2} O _{2}}\)
Question 6
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For the gas phase reaction, \(2 \mathrm{NO}(\mathrm{g})-\mathrm{N}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}), \Delta \mathrm{H}=-43.5\) kcal, which one of the following is true for \(\mathrm{N}_{2}(\mathrm{~g})+\) \(\mathrm{O}_{2}(\mathrm{~g})=2 \mathrm{NO}(\mathrm{g})\)

A

\(\mathrm K\) is independent of \(\mathrm T\)

B
\(\mathrm K\) decreases as \(\mathrm T\) decreases

C
\(\mathrm K\) increases as \(\mathrm T\) decreases

D

\(\mathrm K\) varies with the addition of \(\mathrm NO\)

Solution

The given reaction, \(\mathrm{N}_{2}(\mathrm{~g})+\mathrm{O}_{2}(\mathrm{~g}) \rightleftharpoons 2 \mathrm{NO}(\mathrm{g})\) is endothermic. Therefore, according to Le Chatelier's principle, high temperature favours forward reaction and hence \(\mathrm{K}\) increases as \(\mathrm{T}\) increases or \(\mathrm{K}\) decreases as \(\mathrm{T}\) decreases.
Question 7
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Various oxidation states of few elements are mentioned. Which of the options is not correctly matched?

A
Phosphorus: \(+3\) to \(+5\)

B
Nitrogen: \(+1\) to \(+5\)

C
Iodine: \(-1\) to \(+7\)

D
Chromium: \(-3\) to \(+6\)

Solution

Oxidation number of a element of a group is either equal to the group number (for metals) or 18 - group number (for non-metals). Also, it is equal to the number of valence electrons.
(A)Phosphorous is group 15 and period \(3 .\)
Possible oxidation states are: \(+3\) to \(+5\)
(B) Nitrogen is group 15 and period 2.
Possible oxidation states are: \(+1\) to \(+5\)
(C) lodine is group 17 and period 4.
Possible oxidation states are: \(-1\) to \(+7\)
Group 17 are electronegative elements and have -1 oxidation state.
(D) Chromium is group 6 and period \(4.\)
Possible oxidation states are: \(+1\) to \(+6\). It is a metal and thus cannot show negative oxidation state.
Question 8
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Acetophenone when reacted with a base, \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{ONa}\) yields a stable compound which has the structure:

A

B

C

D

Solution

This is self-aldol condensation [when an aldehyde or ketone in presence of strong base they undergo aldol condensation reaction.
Question 9
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In the first two groups of the periodic table, the group number represents the:

A
Valency

B
Atomic

C
Atomic number

D
Electronegativity

Solution

In the first two groups of the periodic table, the group number represents the valency.
The Group number in the first two groups of the periodic table represents the valency of a particular element.i.e., it represents the number of valence electrons in their outermost shell.For e.g. All Group - I elements have 1 valence electron in their outermost shell and Group - II elements have 2 electrons in their outermost shell.
Question 10
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Direction:The following questions consist of two statements, one labelled as Assertion and the other Reason. Examine both the statements carefully and mark the correct choice according to the instructions given below.
Assertion:Mists are non-viable particulates produced by particles of spray liquids and by condensation of vapours in air.
Reason:Herbicides and insecticides that miss their targets travel through air and form mists.

A
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

B
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

C
Assertion is correct but Reason is incorrect

D
Both Assertion and Reason are incorrect

Solution

Mists are the vapours in the air that undergo condensation. Their production is also possible by liquid sprays. For example: Herbicides and pesticides are used in the form of sprays in agriculture but sometimes it misses its target and enters the atmosphere thereby forming mists. Mists are a non-viable particulate matter which is classified on the basis of size and nature.
So, both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.