1. Which type of compounds cannot exhibit geometrical isomerism?
a) Singly Bonded
b) Doubly Bonded
c) Triply Bonded
d) Cyclic Compounds
Explanation: Triply bonded compounds cannot exhibit geometrical isomerism as the -C=C- bond in these molecules is linear.
2. Choose the correct option from the following.
a) A group gets priority if its atomic number is high
b) When atoms attached to a double bond have same atomic number, the first atoms are considered
c) A group gets priority if its atomic number is low
d) Lone pair gets more priority and is ranked above hydrogen
Explanation: A group gets priority if its atomic number is high and When atoms attached to a double bond have same atomic number, the second atoms are considered.
3. In which type of projection we can get staggered and eclipsed conformations?
a) Newman Projection
b) Sawhorse Projection
c) Fischer Projection
d) Wedge Projection
Explanation: A sawhorse projection can reveal staggered and eclipsed conformations.
4. Which of the following compounds have Z-configuration?
a) CH3CH3CH2>C=C<HCH3
b) HPh>C=C<COOHPh
c) H2NCl>C=C<COOHBr
d) CH3Ph>C=C<CH2CH3Br
Explanation: All the other options are in E-configuration. Only the second option shows the Z-configuration.
5. Select the incorrect option from the following.
a) Fischer projections are two dimensional representations of three dimensional molecules
b) A molecule is achiral if it cannot be superimposed on its mirror reflection
c) E and Z notations are based on Cahn, Ingold and Prelog priority system
d) Chiral molecules which are non-superimposable mirror images of each other are enantiomers
Explanation: A molecule is achiral if it is superimposable on its mirror reflection. All the other options are correct.
6. The cis-trans nomenclature is not applicable when _________
a) The different groups attached to the carbon atom of double bond are same
b) Atleast one of the group attached to each carbon atom is same
c) The different groups attached to the carbon atom of double bond are not same
d) The cis-trans nomenclature is applicable for all compounds
Explanation: The cis-trans nomenclature is applicable when the different groups attached to the carbon atom of double bond are same or atleast one of the group attached to each carbon atom is same.
7. In glyceraldehydes, the complete sequence of priority is _________
a) –OH > -CH2OH > -CHO > -H
b) –H > -CH2OH > -CHO > -OH
c) –H > –OH > -CH2OH > -CHO
d) –OH > CHO > -CH2OH > -H
Explanation: In glyceraldehydes, the complete sequence of priority is –OH > CHO > -CH2OH > -H.
8. Which of the following is not a priority rule for R, S-Configuration?
a) If the four atoms attached to the chiral centre are all different, priority depends on atomic number, with the atom of lower atomic numbers getting lower priority
b) If the two atoms attached to chiral centre are same, the atoms attached to each of these first atoms are compared
c) When there is a double bond or triple bond, both atoms are considered to be duplicated or triplicated
d) If the four atoms attached to the chiral centre are all different, priority depends on atomic number, with the atom of higher atomic numbers getting lower priority
Explanation: If the four atoms attached to the chiral centre are all different, priority depends on atomic number, with the atom of lower atomic numbers getting lower priority.
9. If our eyes travel in counter clockwise direction from the ligand of highest priority to the ligand of lowest priority, the configuration is ____________
a) R-Configuration
b) S-Configuration
c) E-Configuration
d) C-Configuration
Explanation: In S-Configuration, our eyes travel in counter clockwise direction from the ligand of highest priority to the ligand of lowest priority.
10. According to the selection rules, the decreasing order of preference is __________
a) –NH2 > -C6H5 > -CH(CH3)2 > -H
b) –CH(CH3)2 > -C6H5 > -H> -NH2
c) –NH2 > -CH(CH3)2 > -C6H5 > -H
d) -C6H5 > -CH(CH3)2 >–NH2 > -H
Explanation: The atom of higher atomic numbers gets higher priority. So, –NH2 group has the highest priority of all.