Chemistry Multiple Choice Questions on “Green Chemistry”.
1. Which of the following is a greener route to produce ethanal commercially?
a) Catalytic cracking of ethanol
b) Oxidation of ethene with an ionic catalyst
c) Steam reforming of methanol
d) Dehydrogenation of ethylene
Answer: b
Clarification: Ethanal can be prepared by oxidation of ethene, in the presence of an ionic catalyst in an aqueous medium. This is a greener method and gives 90% of yield.
2. Name the conventional solvent that was used for dry cleaning purposes which later confirmed to be a suspected carcinogen.
a) Supercritical CO2
b) Phenanthrene
c) Tetrachloroethene
d) Benzene aldehyde
Answer: c
Clarification: Tetrachloroethene was used as a solvent for dry cleaning purposes. It is a suspected carcinogen and groundwater contaminant. It is replaced by greener solvent like supercritical CO2.
3. Which of the following is not a principle of Green Chemistry?
a) Green solvents and auxiliaries
b) Use of renewable feedstock
c) Hazardous chemical synthesis
d) Design for energy efficiency
Answer: c
Clarification: Synthetic methods should avoid using or generating substances toxic to humans and/or the environment. Hence less hazardous chemical synthesis is an important principle.
4. Green chemistry is the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. Identify the technique used in this area.
a) Bioamplification
b) Polymer manufacturing
c) Pesticide synthesis
d) Use of sunlight and Microwave-assisted reaction
Answer: d
Clarification: Photochemical reaction occurs when light energy gets absorbed by a substances’ molecule. It is a green route as no byproduct will be formed. Vitamin D3 synthesis is assisted by a photochemical reaction.
5. Which of the following gas was traditionally used to bleach paper?
a) Sulfur
b) Carbon dioxide
c) Chlorine
d) Fluorine
Answer: c
Clarification: Chlorine gas was used to bleach paper. It has good oxidizing properties. Nowadays H2O2 with a suitable catalyst is used for bleaching purposes as it does not contaminate groundwater.
6. Replacement of liquid CO2 by halogenated solvent will result in less harm to groundwater.
a) True
b) False
Answer: b
Clarification: Halogenated solvents contaminate groundwater. Whereas liquified CO2 leaves a lower amount of residue. It is also a non-toxic and attractive solvent for temperature-sensitive materials.
7. Which of the following is a green solvent used for bleaching clothes?
a) Hydrogen peroxide
b) Tetrachloroethene
c) Benzene
d) Toluene
Answer: a
Clarification: Hydrogen peroxide can easily breakdown into water and oxygen. It is a good oxidizing agent and a strong bleaching agent. Use of H2O2 gives better results and makes use of a lesser amount of water.
8. Identify the non-toxic and green solvent.
a) Liquified carbondioxide
b) Benzene
c) Carbon tetrachloride
d) Toluene
Answer: a
Clarification: When compared to conventional solvents, liquified CO2 leaves a lower amount of residue. It is also a non-toxic and attractive solvent for temperature-sensitive materials.