Question Set A

cbse 12th Standard Chemistry Biomolecules Model Questions Papers Study Material - QB365

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Questions:

Multiple Choice Question

20 x 1 = 20

Which of the following would not be a good choice for reducing nitrobenzene to aniline?

(a)

LiAlH₄

(b)

H₂/Ni

(c)

Fe and HCI

(d)

Sn and HCl

An \(\alpha\)-helix is a structural feature of

(a)

sucrose

(b)

polypeptides

(c)

nucleotides

(d)

starch

Which one of the following does not constitute the nucleic acid?

(a)

Uracil

(b)

Ribose sugar

(c)

Phosphoric acid

(d)

Guanidine

In the reaction C₆H₅CONH₂ \(\xrightarrow[{\triangle }]{Br_2+KOH}\)Major product A is

(a)

C₆H₆

(b)

C₆H₅CHO

(c)

C₆H₅NH₂

(d)

C₆H₅COOKI

The reaction, \(\begin{equation} \mathrm{ArN}_{2}^{+} \mathrm{Cl}^{-} \stackrel{\mathrm{Cu} / \mathrm{HCl}}{\longrightarrow} \mathrm{ArCl}+\mathrm{N}_{2}+\mathrm{CuCl} \end{equation}\) is named as

(a)

Sandmeyer reaction

(b)

Gattermann reaction

(c)

Claisen reaction

(d)

Carbylamine reaction

Structure of [Ni(CO)₄] is

(a)

tetrahedral

(b)

square planar

(c)

octahedral

(d)

None of these

The hormone that helps in the conversion of glucose into glycogen is

(a)

cortisone

(b)

bile acids

(c)

adrenaline

(d)

insulin

Which gives black precipitate on reaction with CS₂ followed by addition of HgCl₂?

(a)

(CH₃)₃CNH₂

(b)

(C₂H₅)₂NH

(c)

(CH₃)₃N

(d)

all the three

Which of the following is the correct decreasing order of basicity os amines in gaseous phase?

(a)

(CH₃)₂NH > CH₃NH₂ > (CH₃)₃N > NH₃

(b)

(CH₃)₃N > (CH₃)₂NH > CH₃NH₂ > NH₃

(c)

(CH₃)₂NH > (CH₃)₃N > CH₃NH₂ > NH₃

(d)

(CH₃)₃N > CH₃NH₂ > (CH₃)₂NH > NH₃

10.

Which on e of the following amines cannot be prepared by Gabriel phthalimide synthesis?

(a)

Ethylamine

(b)

Isopropylamine

(c)

n-Propylamine

(d)

Ethylmethylamine

11.

Which of the statements about "Denaturation" given below are correct ?
Statements :
(i) Senaturation of proteins causes loss of secondary and tertiary structures of the protein.
(ii) Denaturation leads to the conversion of double strand of DNA into single strand.
(iii) Denaturation affects primary structure which gets distorted.

(a)

(i) and (iii)

(b)

(ii) ad (iii)

(c)

(i) and (ii)

(d)

(i) , (ii), (iii)

12.

The one letter code for the amino acid tryptophan is

(a)

(b)

(c)

(d)

(e)

13.

Glucose when reduced with HI and red phosphorus gives

(a)

n-hexane

(b)

n-heptane

(c)

n-pentane

(d)

n-octane

14.

When a primary amine reacts with chloroform and ethanolic KOH, then the product formed is

(a)

isocyanide

(b)

aldehyde

(c)

cyanide

(d)

alcohol

15.

Which of the following options are correct for \([Fe(CN)_6]^{3-}\) complex ?

(a)

d ²sp³ hybridisation

(b)

sp³d² hybridisation

(c)

paramagnetic

(d)

diamagnetic

16.

A, B and C are three complexes of chromium (III) with the empirical formula H₁₂O₆Cl₃Cr. All the three complexes have water and chloride ions as ligands. Complex A does not react with conc. H₂SO₄ whereas complexes B and C lose 6.75% and 13.5% of their original weight respectively, on treatment with concentrated H₂SO₄.
The complex A is

(a)

[Cr(H₂O)₄(H)₄(O)₂]Cl₃

(b)

[Cr(H₂O₅)₅(H)₂(O)]Cl₃

(c)

[Cr(H₂O)₆]Cl₃

(d)

[Cr(H₂O)₅Cl]Cl₂.H₂O

17.

Which one of the following ligand is caple of forming a low spin as well as a high spin complex?

(a)

(b)

F^-

(c)

NH₃

(d)

CN^-

18.

Square planar complexes of the type MABXL (where A, B, X and L are unidentates) show

(a)

two cis and one trans isomer

(b)

two trans and one cis isomer

(c)

two cis and two trans isomers

(d)

one cis and one trans isomer

19.

The name of the complex ion, [Fe(CN)₆]^3- is:

(a)

tricyanoferrate (III) ion

(b)

hexacyanidoferrate (III) ion

(c)

hexacyano iron (III) ion

(d)

hexacyanitroferrate (III) ion

20.

The ionization isomer of [Cr(H₂O)₄Cl(NO₂)]Cl is

(a)

[Cr(H₂O)₄ (O₂N)] Cl₂

(b)

[Cr(H₂O)₄Cl₂] (NO₂)

(c)

[Cr(H₂O)₄Cl(ONO)] Cl

(d)

Cr(H₂O)₄Cl₂(NO₂)] H₂O

Assertion and reason

20 x 1 = 20

21.

Assertion : At isoelectric point, the amino group does not migrate under the influence of electric field.
Reason : At isoelectric point, amino acid exists as a zwitterion.
Codes:
(a) If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
(b) If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
(c) If the Assertion is correct but Reason is incorrect.
(d) If both the Assertion and Reason are incorrect.

22.

Assertion : Acylation of amines gives a monosubstituted product whereas alkylation of amines gives
poly-substituted product.
Reason : Acyl group sterically hinders the approach of further acyl groups
Codes:
(a) If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
(b) If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
(c) If the Assertion is correct but Reason is incorrect.
(d) If both the Assertion and Reason are incorrect.

23.

Assertion (A) : Complexes of MX₆ and MX₅L type (X and L are unidentate) do not show geometrical isomerism.
Reason (R) : Geometrical isomerism is not shown by complexes of coordination number 6
(a) Both (A) and (R) are correct but (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct but (R) is not the correct explanation of (A).
(c) (A) is correct but (R) is incorrect.
(d) (A) is incorrect but (R) is correct.

24.

Assertion (A) Proteins are polymers of \(\alpha\)-amino acids connected by peptide bond.
Reason (R) A tetrapeptide contains 4 amino acids linked by 4 peptide bonds.
(a) Both (A) and (R) are correct and (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct but (R) is not the correct explanation of (A).
(c) (A) is correct but (R) is incorrect.
(d) (A) is incorrect but (R) is correct.

25.

Assertion: Glycine must be taken through diet.
Reason: It is an essential amino acid.
Codes:
(a) Assertion and reason both are correct and reason is correct explanation of assertion.
(b) Assertion and reason both are wrong statements.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.
(e) Both assertion and reason are correct statements but reason is not correct explanation of assertion.

26.

Assertion: Alpha (\(\alpha \))-amino acids exist as internal salt in solution as they have amino and carboxylic acid groups in near vicinity.
Reason: H⁺ ion given by carboxylic group (-COOH) is captured by amino group (-NH₂) having lone pair of electrons.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

27.

Assertion: Nitration of aniline can be done conveniently by protecting the amino group by acetylation.
Reason: Acetylation increases the electron density in the benzene ring.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

28.

Assertion: Aniline hydrogen sulphate, on heating, forms p-aminosulphonic acid.
Reason: The sulphonic acid group is electron-withdrawing.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

29.

Assertion: Aniline is a weaker base than cyclohexylamine.
Reason: Aniline undergoes halogenation even in the absence of a catalyst.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

30.

Assertion: In Hoffmann bromamide reaction, the amine formed has one carbon atom less than the parent 1°amide.
Reason: N-methyl acetamide undergoes Hoffmann bromamide reaction.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

31.

Assertion: Zeises salt is a ㅠ-bonded organometallic compound.
Reason: The oxidation number of platinum in Zeises salt is +2.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

32.

Assertion: All the octahedral complexes of Ni²⁺ must be outer orbital complexes.
Reason: Outer orbital octahedral complexes are given by weak ligands.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement

33.

Assertion: Low spin complexes have less number of unpaired electrons.
Reason: [FeF₆]^3- is a low spin complex.
Codes:
(a) Assertion and reason both are correct statements and reason is correct explanation for assertion.
(b) Assertion and reason both are correct statements but reason is not correct explanation for assertion.
(c) Assertion is correct statement but reason is wrong statement.
(d) Assertion is wrong statement but reason is correct statement.

34.

In the following questions. an Assertion (A) is followed by a corresponding Reason (R) Use the following keys to choose the appropriate answer.
Assertion (A) DNA is responsible for maintaining the identity of different species of organisms over millions of years.
Reason (R) DNA molecule is capable of self duplication during cell division and identical DNA strands are transferred to daughter cell.
Codes:
(a) Both (A) and (R) are correct, (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct, (R) is not the correct explanation of (A).
(c) (A) is correct; (R) is incorrect.
(d) (A) is incorrect; (R) is correct.

35.

In the following questions. an Assertion (A) is followed by a corresponding Reason (R) Use the following keys to choose the appropriate answer.
Assertion (A) The coagulation of egg white occur on boiling.
Reason (R) Denaturation of protein is occur when its native form is subjected to physical change or chemical change.
Codes:
(a) Both (A) and (R) are correct, (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct, (R) is not the correct explanation of (A).
(c) (A) is correct; (R) is incorrect.
(d) (A) is incorrect; (R) is correct.

36.

In the following questions. an Assertion (A) is followed by a corresponding Reason (R) Use the following keys to choose the appropriate answer.
Assertion (A) Acylation of amines gives a monosubstituted product, whereas alkylation of amines gives polysubstituted product.
Reason (R) Acyl group sterically hinders the approach of further acyl groups.
Codes:
(a) Both (A) and (R) are correct, (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct, (R) is not the correct explanation of (A).
(c) (A) is correct; (R) is incorrect.
(d) (A) is incorrect; (R) is correct.

37.

In the following questions. an Assertion (A) is followed by a corresponding Reason (R) Use the
following keys to choose the appropriate answer.
Assertion (A) Acetanilide is less basic than aniline.
Reason (R) Acetylation of aniline results in decrease in decrease of electron density of nitrogen.
Codes:
(a) Both (A) and (R) are correct, (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct, (R) is not the correct explanation of (A).
(c) (A) is correct; (R) is incorrect.
(d) (A) is incorrect; (R) is correct.

38.

In the following questions. an Assertion (A) is followed by a corresponding Reason (R) Use the following keys to choose the appropriate answer.
Assertion (A) [Ni(CN)₄]^2- is square planar and dimagnetic.
Reason (R) It has no unpaired electrons due to presence of strong field ligand.
Codes:
(a) Both (A) and (R) are correct, (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct, (R) is not the correct explanation of (A).
(c) (A) is correct; (R) is incorrect.
(d) (A) is incorrect; (R) is correct.

39.

In the following questions. an Assertion (A) is followed by a corresponding Reason (R) Use the following keys to choose the appropriate answer.
Assertion (A) The stability of \(\begin{equation} \left[\mathrm{Ni}(\mathrm{en})_{3}\right] \mathrm{Cl}_{2} \end{equation}\) is lower than that of \(\begin{equation} \left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{6}\right] \mathrm{Cl}_{2} \end{equation}\)
Reason (R) The geometry of Ni is trigonal bipyramidal in \(\begin{equation} \left[\mathrm{Ni}(\mathrm{en})_{3}\right] \mathrm{Cl}_{2} \end{equation}\).
Codes:
(a) Both (A) and (R) are correct, (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct, (R) is not the correct explanation of (A).
(c) (A) is correct; (R) is incorrect.
(d) (A) is incorrect; (R) is correct.

40.

In the following questions. an Assertion (A) is followed by a corresponding Reason (R) Use the following keys to choose the appropriate answer.
Assertion (A) In the coordination compound \(\begin{equation} \left[\mathrm{Co}\left(\mathrm{H}_{2} \mathrm{NCH}_{2} \mathrm{CH}_{2} \mathrm{NH}_{2}\right)_{3}\right]_{2} \end{equation}\),ethane-1,2-diamine is a neutral ligand.
Reason (R) Oxidation number of Co in the complex ion is +3.
Codes:
(a) Both (A) and (R) are correct, (R) is the correct explanation of (A).
(b) Both (A) and (R) are correct, (R) is not the correct explanation of (A).
(c) (A) is correct; (R) is incorrect.
(d) (A) is incorrect; (R) is correct.

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Answers Key:

Multiple Choice Question

20 x 1 = 20

(a)
LiAlH₄

(b)
polypeptides

(d)
Guanidine

(b)
C₆H₅CHO

(b)
Gattermann reaction

(a)
tetrahedral

(d)
insulin

Only \({ 1 }^{ \circ }\) amines undergo Hofmann Mustard oil reaction and thus give a black ppt. of HgS.

In the gaseous phase, basicity increases as the +I effect of the alkyl groups increases. Thus, option (b) is correct.

10.

Only \({ 1 }^{ \circ }\) amines can be prepared by Gabriel phthalimide reaction. Therefore, ethylmethylamine being \({ 2 }^{ \circ }\) cannot be prepared by this method.

11.

12.

13.

(a)
n-hexane

14.

Carbylamine reaction yields isocyanides.

15.

(a)
d ²sp³ hybridisation

16.

17.

18.

(a)
two cis and one trans isomer

19.

(b)
hexacyanidoferrate (III) ion

20.

(b)
[Cr(H₂O)₄Cl₂] (NO₂)

Assertion and reason

20 x 1 = 20

21.

(a) If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.

22.

23.

(c) (A) is correct but (R) is incorrect.
Complexes of MX₆ and MX₅L type (X and L are unidentate) do not show geometrical isomerism due to presence of plane of symmetry.

24.

(c) (A) is correct while (R) is incorrect. The correct (R) statement is a tetrapeptide contains 4 amino acids linked by three peptide bonds.

25.

(b) Both assertion and reason are wrong statements.
Glycine is not essential amino acid because it is produced in our body, so it may not be part of our diet.

26.

\(\text { (a): } \mathrm{NH}_{2}-\mathrm{CH}_{2}-\mathrm{COOH}\) is a typical \(\alpha \) -amino acid.
In solution it exists as, internal salt or zwitter ion,
\(\left(\mathrm{NH}_{3}-\mathrm{CH}_{2}-\mathrm{COO}^{-}\right)\)
because the proton (H⁺) of - COOH group is captured by - NH₂ group as NH₂ has a lone pair of electrons on N atom.

27.

(c): Acetylation decreases the electron density in the benzene ring and deactivate the ring hence control the reaction.

28.

(b): -NH₂ being o,p-directing group directs -SO₃H group to less hindered p-position.

29.

(b): Aniline exists as resonance hybrid. As a result of resonance, the lone pair of electrons on nitrogen gets delocalized over the benzene ring and thus, is less easily available for protonation than in case of cyclohexylamine where no such resonance takes place.

30.

(c): Only primary amines can be prepared from amides (RCONH₂ ) by treating with Br₂ and KOH. Thus, N-methyl acetamide i.e., CH₃CONHCH₃ does not undergo Hoffmann bromamide reaction.

31.

(b): In these complexes, the metal and ligand form a bond that involves the rt-electrons of the ligand and so it is a ㅠ -bonded organometallic compound.

32.

(b): Ni²⁺ configuration.

During rearrangement only one 3d-orbital may be made available by pairing the electrons. Thus, inner d2sp3 hybridisation is not possible. So, only sp³d²(outer) hybridisation can occur.

33.

(c): [FeF₆]^3- is a high spin complex since F^- is a weak field ligand.

34.

(a) DNA is the chemical basis of heredity and may be regarded as the reserve of genetic information. DNA is exclusively responsible for maintaining the identity of different species of organisms over millions of years. A DNA molecule is capable of self duplication during cell division and identical DNA strands are transferred to the daughter cells. Hence, Both (A) and (R) are correct and (R) is correct explanation of (A).

35.

(a) When a protein in its native form is subjected to physical change like change in temperature or chemical change like change in pH, the hydrogen bonds are disturbed.
Due to this, globules unfold and helix get uncoiled and protein loses its biological activity. This is called denaturation of protein. The coagulation of egg white on boiling is the common example of denaturation. Thus, both (A)and (R)are correct explanation of (A).

36.

(c) Acylation of amine gives a mono substituted product whereas alkylation of amine gives polysubstituted product because acylation in amine takes place at N-atom and alkylation takes place at o-and p-position. Hence, (A) is correct but (R) is incorrect.

37.

(a) Both A and R are correct and R is the correct explanation of A.

38.

[Ni(CN)₄]^2- is square planar and dimagnetic.
\(\begin{equation} \begin{array}{l} \mathrm{Ni} \rightarrow 3 d^{8} 4 s^{2} \\ \mathrm{Ni}^{2+} \rightarrow 3 d^{8} 4 s^{0} \end{array} \end{equation}\)

\(\therefore\)This complex has no unpaired electron.
Both (A) and (R) are correct and (R) is the correct explanation of (A).

39.

(c) \(\begin{equation} \left[\mathrm{Ni}(\mathrm{en})_{3}\right] \mathrm{Cl}_{2} \end{equation}\) is more stable than \(\begin{equation} \left[\mathrm{Ni}\left(\mathrm{NH}_{3}\right)_{6}\right] \mathrm{Cl}_{2} \end{equation}\), because \(\begin{equation} \left[\mathrm{Ni}(\mathrm{en})_{3}\right] \mathrm{Cl}_{2} \end{equation}\) is a chelating compound which are more stable than complexes with unidentate ligands as the dissociation of complex involves breaking of two bonds instead of one. \(\begin{equation} \left[\mathrm{Ni}(\mathrm{en})_{3}\right] \mathrm{Cl}_{2} \end{equation}\)show octahedral geometry with d⁸ configuration. (A) is correct but (R) is incorrect.

40.

(b) Ethane-1, 2-diamine is a neutral ligand as it carries no charge. Oxidation number of Co in the complex ion is +3. Both (A) and (R) are correct but (R) is not the correct explanation of (A).