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Chemistry M.C.Q [1M]

MODEL PAPER 1 · Bihar Board (BSEB) STD 12 Science (BSEB - English Medium). 12 questions.

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M.C.Q [1M]

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12 questions · timed · auto-graded

MCQ 11 Mark
Which of the following methods of preparation of amines will give same number of carbon atoms in the chain of amines as in the reactant?
  • ✓
    Treatment of amide with bromine in an aqueous solution of sodium hydroxide
  • B
    Heating alkylhalide with potassium salt of phthalimide followed by hydrolysis
  • C
    Reaction of nitrite with LiAlH4
  • D
    Reaction of amide with LiAlH4 followed by treatment with water
Answer
Correct option: A.
Treatment of amide with bromine in an aqueous solution of sodium hydroxide
(a) Treatment of amide with bromine in an aqueous solution of sodium hydroxide
Explanation: Aliphatic and aryl/alkyl primary amines can be prepared by the reduction of the corresponding nitriles with lithium aluminium hydride LiAIH4.
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Heating alkyl halide with primary, secondary, and tertiary amine can be prepared by reduction of LiAlH4 ether followed by treatment with water.
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Heating alkyl halide with potassium salt of phthalimide followed by hydrolysis produces primary amine. This process is known as Gabriel's phthalimide reaction. The number of carbon atoms in the chain of amines of the product is the same as a reactant.
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MCQ 21 Mark
The conversion of an alkyl halide into alcohol by aqueous NaOH is classified as
  • A
    a dehydrohalogenation reaction
  • ✓
    a substitution reaction
  • C
    an addition reaction
  • D
    a dehydration reaction
Answer
Correct option: B.
a substitution reaction
(b) a substitution reaction
Explanation: Alkyl halides on alkaline hydrolysis (aqueous NaOH) get converted into alcohol. This takes place by a nucleophilic substitution reaction where the -X atom is substituted by a nucleophile i.e -OH group. The primary alkyl halides undergo nucleophilic substitution reaction by SN2 substitution mechanism, while tertiary alkyl halides follow SN1 substitution mechanism.
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MCQ 31 Mark
Match the items given in column I with that in column II.
Column IColumn II
(a) Molarity(1) $\frac{\text { Mass of solute }}{\text { Mass of solution }} \times 10^6$
(b) Molality(2) Number of gram moles of a solute per litre of solution
(c)Normality(3) Number of gram moles of a solute per kg of solvent
(d) ppmiv) Number of gram equivalent of a solute per litre of solution
  • ✓
    (a) (2), (b) - (3), (c) - (4), (d) - (1)
  • B
    (a) (4), (b) - (3), (c) - (2), (d) - (1)
  • C
    (a)-(3), (b) - (2), (c) - (1), (d) - (4)
  • D
    (a)-(1), (b) - (2), (c) - (3), (d) - (4)
Answer
Correct option: A.
(a) (2), (b) - (3), (c) - (4), (d) - (1)
(a) (a)-(2), (b) - (3), (c) - (4), (d) - (1)
Explanation: (a) - (2), (b) - (3), (c) - (4), (d) - (1)
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MCQ 41 Mark
Which one of the following compounds is more reactive towards SN1 reaction?
Answer
Correct option: A.
C6H5CH(C6H5)Br
(a) C6H5CH(C6H5)Br
Explanation: C6H5CH(C6H5)+ carbocation formed is more stable.
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MCQ 71 Mark
Chlorine reacts with cold and dilute NaOH to give
  • A
    NaCIO and NaCIO3
  • B
    NaCl and NaCIO3
  • ✓
    NaCl and NaCIO
  • D
    NaCl and NaCIO4
Answer
Correct option: C.
NaCl and NaCIO
(c) NaCl and NaCIO
Explanation: Chlorine reacts with cold and dilute NaOH to produce a mixture of sodium chloride (NaCl) and sodium hypochloride (NaOCl).
2NaOH + Cl2 → NaCl + NaOCl + H2O
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MCQ 81 Mark
Anisole can be prepared by the action of methyl iodide on sodium phenate. The reaction is called
  • A
    Fittigs reaction
  • B
    Wurtzs reaction
  • ✓
    Williamsons reaction
  • D
    Etards reaction
Answer
Correct option: C.
Williamsons reaction
(c) Williamsons reaction
Explanation: The reaction of an alkyl halide with sodium alkoxide to give ether (alkoxy alkane), is known as Williamson's synthesis. In this reaction, an ether (anisole) is prepared by the action of alkyl halide (methyl iodide) on sodium alkoxide (sodium phenate), so it is an example of Williamson's synthesis.
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MCQ 91 Mark
β-pleated sheet structure in proteins refers to
  • A
    tertiary structure
  • B
    primary structure
  • C
    quaternary structure
  • ✓
    secondary structure
Answer
Correct option: D.
secondary structure
(d) secondary structure
Explanation: Alpha helices and beta sheets are the two most known secondary structures of protein, As the protein folds into a three-dimensional structure, the secondary structure forms an intermediate.
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MCQ 111 Mark
The incorrect statement about interstitial compounds is:
  • A
    They retain metallic conductivity.
  • B
    They are very hard.
  • ✓
    They are chemically reactive.
  • D
    They have high melting point.
Answer
Correct option: C.
They are chemically reactive.
(c) They are chemically reactive.
Explanation: Interstitial compounds are obtained when small atoms like H, B, C, resemble N, etc. fit into the lattice of other elements. They are chemically inert
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MCQ 121 Mark
The ionic reactions are generally very fast because
  • ✓
    It does not involve bond breaking
  • B
    The number of collisions between ions are very large
  • C
    Reactions are highly exothermic
  • D
    The energy of interaction between charged ion is greater than between neutral molecules
Answer
Correct option: A.
It does not involve bond breaking
(a) It does not involve bond breaking
Explanation: Ionic reactions do not involve bond breaking, energy is directly used in completing the reaction, therefore they are fast.
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