Chemistry Test

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Chemistry Test - 10

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Weekly Quiz Competition

Question 1
3 / -1

Identify the product formed in Friedal-Crafts reaction of acetyl chloride.

A
Ketone

B
Benzene

C
Aldehyde

D
Phenol

Solution

Acyl chlorides react with aromatic hydrocarbons in Friedel Crat acylation reaction to produce aromatic ketone. Acetyl group (CH₃ − CO) is introduced in benzene ring. It is electrophilic aromatic substitution reaction.
Hence option A is correct answer.
Question 2
3 / -1

Which of the following statements is/are correct?

A
If for a reaction, ΔH is −ve and ΔS is + ve, then the reverse reaction is always non-spontaneous at all temperatures

B
If ΔH is + ve and ΔS is − ve, then the forward reaction is non-spontaneous at all temperatures

C
If both ΔH and ΔS are − ve, then the reverse reaction is spontaneous at high temperatures

D
All of the above

Solution

$\Delta G=\Delta H-T \Delta S$
A) $\Delta G$ is always $-$ ve; the forward reaction is spontaneous and backward reaction is always non-spontaneous.
$\Delta G$ is always $+$ ve; the forward reaction is non-spontaneous at all temperatures.
C) $\Delta G$ is - ve at low temperatures and $+$ ve at high temperatures; the forward reaction is spontaneous at low temperatures.
Hence option D is the correct answer.
Question 3
3 / -1

The acid which does not form an anhydride when treated with P₂O₅ is:

A
Formic acid

B
Acetic acid

C
Propionic acid

D
Benzoic acid

Solution

Phosphorus pentoxide is a dehydrating agent.
It abstracts a molecule of water from formic acid to form carbon dioxide. $H C O O H \overset{R O_{3}}{⟶} C O_{2} + H_{2} O$
Thus, formic acid which does not form an anhydride when treated with P₂O₅.
Hence option A is the correct answer.
Question 4
3 / -1

A

B

C

D

Solution

The first reaction is nitration of benzene to give nitrobenzene(W) $C_{6} H_{6}+H N O_{3} / H_{2} S O_{4} \rightarrow C_{6} H_{5} N O_{2}$
The second reaction is reduction of nitrobenzene to aniline $C_{6} H_{5} N O_{2}+Z n / H C l \rightarrow C_{6} H_{5} N H_{2}$
The third reaction is formation of arenediazonium salt. $C_{6} H_{5} N H_{2}+N a N O_{2}-H C l \rightarrow C_{6} H_{5} N_{2}^{+} C l$
The fourth step is hydrolysis of arene diazonium salt to give benzene $C_{6} H_{5} N_{2}^{+} C l^{-}+H_{2} O / H_{3} P O_{2} \rightarrow C_{6} H_{6}$

Hence option B is the correct answer.
Question 5
3 / -1

If concentration of two weak acids are different and degree of ionization (α) is very less, then their relative strength can be compared by:

A
[H⁺]₁ / [H⁺]₂

B
α1 / α2

C
Ka₁C₁ / Ka₂C₂

D
All of the above

Solution

The Relative strength (R.S) $=\frac{\left[H^{+} \mid\right. \text {furnirhed by acid } I}{\left[H^{+}\right] \text {furnishod by acid } I I}=\frac{C_{1} \alpha_{1}}{C_{2} \alpha_{2}}=\frac{C_{1}}{C_{2}} \times \sqrt{\frac{K_{a_{1}} C_{2}}{K_{02} C_{1}}}=\sqrt{\frac{K_{a_{1}} C_{1}}{K_{a_{2}} C_{2}}}$
Relative strength of various acids can be compared using $K_{a}$ larger the value of $K_{a}$, the stronger the acid. So their relative strength can be compared by $\frac{\left.\mid H^{+}\right]_{1}}{\left[H^{+}\right]_{2}}$

Hence option A is the correct answer.
Question 6
3 / -1

Which of the following is a non-reducing sugar?

A
glucose

B
sucrose

C
fructose

D
lactose

Solution

There is no free aldehyde group present in sucrose due to the glycosidic linkage. While in others, there is a free aldehydic/ketonic group present. If an aldehydic group is present, the molecules can reduce various compounds (reagents), which are also used as a test for the same. Even if ketonic group is present, it isomerizes to aldehydic group. So, sucrose is a nonreducing sugar.
Hence option B is the correct answer.
Question 7
3 / -1

Which of the following is not correct regarding terylene?

A
Step-growth polymer

B
Synthetic bre

C
Condensation polymer

D
Thermosetting plastic

Solution

Terylene is a synthetic polyester bre or fabric based on terephthalic acid, charectrized by lightness and crease resistance and used for clothing, sheets, ropes, sails, etc. It is produced by polymerizing terephthalic acid and ethylene glycol using condensation techniques. Thermosetting plastics are polymer materials which are liquid or malleable at low temperatures, but which change irreversibly to become hard at high temperatures.
Terylene is not a thermosetting plastic hence option D is correct.
Question 8
3 / -1

Which of the following statements is/are correct?

A
Boric acid is a hydrogen-bonded molecule

B
Boric acid combines with CuO to give meta borate in the borax bead test

C
Boric acid is a lewis acid

D
All of the above

Solution

A) Boric acid molecules are $H$ - bonded as shown in the given structure.
B) Boric acid, on heating gives a mixture of $H B O_{2}+B_{2} O_{3}$ which react with $C u O$ to give $C u\left(B O_{2}\right)_{2}$ (blue bead in borax bead test)
C) A lewis acid is an electron pair acceptor. The boron atom in boric acid, $B(O H)_{3},$ has an empty shell, able to accept a fourth electron pair. For example, it can accept oxygen's electrons in an acid-base reaction with water:
$B(O H)_{3}+H_{2} O \rightarrow B(O H)_{4}+H^{+}$
Hence option D is the correct answer.
Question 9
3 / -1

Acetic anhydride with Benzene in presence of anhydrous gives: AlCl₃.

A
acetyl chloride

B
acetophenone

C
benzophenone

D
none of the above

Solution

It is an example of Friedel Crat acylation reaction in which acetyl group (CH3 − CO) is introduced in benzene ring. It is electrophilic aromatic substitution reaction.
Question 10
3 / -1

2CaSO4(s)⇌2CaO(s)+2SO2(g)+O2(g),ΔH>0

Above equilibrium is established by taking sufficient amount of CaSO₄(s) in a closed container at 1600 K. Then which of the following may be correct option(s)?

(Assume that solid CaSO₄ is present in the container in each case)

A
Moles of CaO(s) will increase with the increase in temperature

B
If the volume of the container is halved partial pressure of O₂(g) at new equilibrium will remain same

C
If two moles of He gas is added at constant pressure then the moles of CaO(s) will increase.

D
None of these

Solution

For endothermic reaction $(△ H > 0)$ if temperature increases equlibrium shift towards right. Therefore option A is correct. For any change in the volume in the container not going to change the equilibrium pressure at a given temperature if the CaSO₄ is available. Therefore Partial pressure of SO₂will not change. incorrect. Same reason as for B.

Hence option A is the correct answer.
Question 11
3 / -1

Vinyl bromide undergoes:

A
addition reaction

B
substitution reaction

C
rearrangement reaction

D
All of the above

Solution

Vinyl Bromide $(B r C H = C H_{2})$ shows both addition and elimination reactions. In addition reaction $π$ , bond breaks and it forms ethyl bromide and in elimination reactions hydrogen bromide eliminates and forms allyyne. Substitution is not possible as that would mean sp² a carbon having a positive charge, which is unfavorable. Rearrangement reaction is also not possible because of the simple reason that there are only two carbon atoms and rearrangement to a different structure cannot happen, as no other structure exists.

Hence option A is the correct answer.
Question 12
3 / -1

Identify the correct statement(s) out of the following:
a. Deciency of vitamin A causes xerophthalmia
b. The function of vitamin C is maintenance of redox potentials of cells
c. Vitamin B12 contain ionone ring.
d. Folic acid (vitamin B9) consists of corrin ring.

A
a only

B
a and b

C
a, b and c

D
all

Solution

Option (B) is correct. A. Deciency of vitamin causes xerophthalmia. It is a condition in which an eye becomes abnormally dry because it can't maintain an adequate layer of tears to coat its surface. B. The function of vitamin C is maintenance of redox potentials of cells important for defence against infections such as common colds. It also acts as an inhibitor of histamine, a compound that is released during allergic reactions. As a powerful antioxidant it can neutralize harmful free radicals and it aids in neutralizing pollutants and toxins.
C. Vitamin A contain ionone ring. All forms of vitamin A have acbeta - ionone ring to which an isoprenoid chain is attached, called a retinyl group.
D. Folic acid (vitamin B₁₂ ) consists of corrin ring. It contains a cobalt ion as part of the porphyrin-like corrin ring.
Hence option B is the correct answer.
Question 13
3 / -1

Which of the following reactions is called Rosenmund reaction?

A
Aldehydes are reduced to alcohols

B
Acids are converted to acid chlorides

C
Alcohols are reduced to hydrocarbons

D
Acid chloride are reduced to aldehydes

Solution

in Rosenmund reaction, acid chloride are reduced to aldehydes.
[The Rosenmund reduction is a hydrogenation process in which an acyl chloride is selectively reduced to an aldehyde. The reaction was named after Karl Wilhelm Rosenmund, who first reported it in 1918.]
Hence option D is the correct answer.
Question 14
3 / -1

Identify the co-polymer from the following:

A
[−CH₂ − CH = CH₂ − CH₂ − CH(C₆H₅ ) − CH₂−]n

B
[−CF₂ − CF₂−]n

C
[−CH₂ − C(Cl) = CH − CH₂−]n

D
[−CH₂ − CH(Cl)−]n

Solution

SBR (Buna S),
[−CH₂ − CH = CH₂ − CH₂ − CH(C₆H₅ ) − CH₂−]n
is a co-polymer. It is made from 2 monomers 1,3-butadiene and styrene. It is an example of addition polymerisation. Note: Two or more types of monomers are used in the preparation of a co-polymer.
Hence option A is the correct answer.
Question 15
3 / -1

When ethyl alcohol is passed over red hot copper at 300°C, the formula of the product formed is

A
CH₃CHO

B
CH₃COCH

C
C₂H₄

D
CH₃COOH

Solution

When ethyl alcohol is passed over red hot copper at 300°C, the product formed is acetaldehyde, CH₃CHO
The reaction is as follows: $C_{2} H_{5} O H \frac{red hot C u}{300 ° C} C H_{3} C H O$
Hence option A is the correct answer.