M.C.Q (1 Marks)

Question 11 Mark

Aniline does not undergo Friedel - Crafts reaction because:

Answer

(b) Aluminium chloride reacts with Aniline
Explanation: $AlCl _3$ being a lewis acid reacts with the lone pair of $- NH _2$ group of aniline forming an adduct $\left( C _6 H _5 NH _2{ }^{+} AlCl _3\right)$ which deactivates the benzene system hence no friedal craft reaction occurs.

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Question 21 Mark

Williamson's synthesis is used for the preparation of

Answer

The Williamson ether synthesis is an organic reaction, forming an ether from an organohalide and deprotonated alcohol $($alkoxide$).$ This reaction was developed by Alexander Williamson in $1850.$ Typically it involves the reaction of an alkoxide ion with a primary alkyl halide via an $S_N2$ reaction.

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Question 31 Mark

The reduction of ethanenitrile with sodium and alcohol gives:

Answer

(a) 1-aminoethane
Explanation: 1-aminoethane

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Question 41 Mark

The reaction $A \rightarrow B$ is a second order process when the initial concentration of $A$ is $0.50 M$, the half life is $8.0$ minutes. What is the half life if the initial concentration of $A$ is $0.10 M?$

Answer

$(a) 40.0$ minutes
Explanation: For second$-$order reaction:
$t_{1 / 2}=\frac{2 k}{[R]}$
$\Rightarrow k=\frac{t_{1 / 2}[R]}{2}$
Applying this equation,
$\frac{t_{1 / 2}[R]}{2}=\frac{t_{1_{1 / 2}}\left[R^{\prime}\right]}{2}$
$\frac{8.0 \times 0.50}{2}=\frac{t_{1 / 2}^{\prime} \times 0.10}{2}$
$t_{1 / 2}^{\prime}=\frac{8 \times 0.50}{0.10}=40$

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Question 51 Mark

The compound which forms acetaldehyde when heated with dilute NaOH is:

Answer

(d) 1, 1 dichloroethane
Explanation: $CH _3 CHCl _2+ OH ^{-} \rightarrow CH _3 CH ( OH )_2 \rightarrow CH _3 CHO + H _2 O$
Gem diols like $\left( CH _3 CH ( OH )_2\right.$ ) are generally not stable. The $2- OH$ group attached to the same C removes $H _2 O$ and forms carbonyl compounds.

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Question 61 Mark

Silver ornaments turn black by the presence of which gas in the atmosphere?

Answer

Silver ornaments turns black coming in contact with $\ce{H_2S}$ due to formation of $\ce{Ag_{2}S}.$
The chemical equation for this change can be represented as given below: $\ce{2Ag(s) + H_2S(g) Ag_{2}S(s) + H_2(g)}$

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Question 71 Mark

$\ce{CH_3CONH_2}$ on reaction with $\ce{NaOH}$ and $Br_2$ in alcoholic medium gives$:$

Answer

Product formed is $\ce{CH_3NH_2}$

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Question 81 Mark

Answer

(b) 1-Bromo-2-methylbutane
Explanation: First, we need to identify the longest carbon chain. Once we do that, the actual structure should read $CH _3- CH _2$ $- CH \left( CH _3\right)- CH _2- Br$. - Br , the functional halide group is attached to the first carbon atom (1- Bromo), so we start the numbering from that position. The methyl group branch is bond to the second carbon atom in the chain(2-methyl). The number of carbons in the unbranched parent chain is four, thus giving the name butane. The IUPAC is named 1-Bromo-2methylbutane.

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Question 91 Mark

Chlorobenzene is formed by the reaction of chlorine with benzene in the presence of $\ce{AlCl_3}.$ Which of the following species attacks the benzene ring in this reaction?

Answer

Aluminum chloride $\ce{( AlCl_3)}$ is a Lewis acid catalyst and works in the same way as $\ce{FeCl_3}$ does. Benzene $\ce{( C_6H_6)}$ is converted into chlorobenzene by chlorination of benzene in the presence of $\ce{AlCl_3}.$ The reaction occurs by an electrophilic substitution reaction. $\ce{Cl_2}$ forms a coordination complex with $\ce{AlCl_3}$, forming $\ce{Cl ^{+} AlCl_4^{-}}$ complex, which gives a slight positive charge to $Cl ,$ and $\ce{AlCl_4^{-}}$ is negatively charged. This $Cl ^{+}$ then reacts with the aromatic double bond of the benzene ring to form an additional product, followed by deprotonation to form chlorobenzene and $\ce{AlCl_3}$ and $\ce{HCl}$ as the side products.

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Question 101 Mark

The following experimental rate data were obtained for a reaction carried out at $25^{\circ} C : A_{(g)}+B_{(g)} \rightarrow C_{(g)}+D_{(g)}$

Initial $[A_{(g)}] \ce{mol dm^{-3}}$	Initial $[B_{(g)}]\ce{mol dm^{-3}}$	Initial rate $\ce{mol dm^{-3}S^{-1}}$
$3.0 \times 10^{-2}$	$2.0 \times 10^{-2}$	$1.89 \times 10^{-4}$
$3.0 \times 10^{-2}$	$4.0 \times 10^{-2}$	$1.89 \times 10^{-4}$
$6.0 \times 10^{-2}$	$4.0 \times 10^{-2}$	$7.56 \times 10^{-4}$

Answer

Order with respect to $A_{(g)}$
Second Order with respect to $B_{(g)} -$ Zero

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Question 111 Mark

Match the items given in column $I$ with that in column $II:$

Column $I$	Column $II$
$(a)$ Urea	$(i) i < 1$
$(b) \ce{FeCl_3}$	$(ii) i = 1$
$(c)$ Benzoic acid in Benzene	$(iii) i = 2$
$(d) \ce{MgSO_4}$	$(iv) i = 4$

Answer

$(a)-(ii), (b)-(iv), (c) - (i), (d) - (iii)$

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Question 121 Mark

Which of the following reactions of glucose can be explained only by its cyclic structure?

Answer

(b) Pentaacetate of glucose does not react with hydroxylamine.
Explanation: The pentaacetate of glucose does not react with the hydroxylamine indicating the absence of free -CHO group. This property of the glucose can be explained only by its own cyclic structure.

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Chemistry M.C.Q (1 Marks)

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