Multiple Choice QuestionsWhich one of the following oxides is reduced by water gas to obtain the metal during its extraction?
NiO
ZnO
WO3
Fe2O3
0.16 g of an organic compound containing sulphur produces 0.233 g of BaSO4. Percentage of sulphur in the compound is
20
80
50
10
The order of reactivity of phenol (I), nitrobenzene (II) and benzene (III) towards nitration is
(III) > (I) > (II)
(II) > (III) > (I)
(I) > (III) > (II)
(I) > (II) > (III)
The pKa values of four carboxylic acids are 4.76, 4.19, 0.23 and 3.41 respectively. The pKa value ofstrongest carboxylic acid among them is
4.19
3.41
0.23
4.76
Which one of the following statements is not correct?
Except glycine all other naturally occurring α-amino acids are optically active.
α-amino acids have maximum solubility at their isoelectric point.
A tripeptide has two peptide bonds.
α-amino acids exist as Zwitter ions.
Which one of the following is true for an exothermic reaction A B, if Ef and Eb are the activation energies of forward and backward reactions respectively?
Ef > Eb
Ef = Eb
Ef = -Eb
Ef < Eb
Assertion (A) : Cyclohexane is the most stable cycloalkane.
Reason (R) : Cyclopropane and cyclobutane are less stable due to angle starin and torsional strain.
The correct answer is-
Both (A) and (R) are true but (R) is not the correct explanation of (A).
(A) is true but (R) is not true.
(A) is not true but (R) is true.
Both (A) and (R) are true and (R) is the correct explanation of (A).
A.
Both (A) and (R) are true but (R) is not the correct explanation of (A).
In cycloalkane the heat of combustion of cyclohexane (657.9 kJ mol-1) is the lowest, hence, it is the most stable cycloalkane. Cyclopropane and cyclobutane are less stable due to angle strain and torsional strain, therefore cyclopropane and cyclobutane are reactive cycloalkane.
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