All Free Chemistry MCQs with Answers

• A. Coal tar
• B. Petroleum
• C. Coal
• D. Natural gas

Explanation: It is a black, combustible rock primarily composed of carbon. It is used as a fuel source for power generation and in industrial processes.

• A. Chlorofluorocarbons
• B. SO2
• C. Smog
• D. Photochemical oxidation

Explanation: The ozone layer in the upper atmosphere is being primarily destroyed by chlorofluorocarbons (CFCs).

• A. m-directing
• B. o-directing
• C. o -& p -directing & deactivating
• D. o -& p -directing & activating

Explanation: Chlorine has a lone pair, so it can donate electrons to the benzene ring.

• A. C2H5
• B. SO3H
• C. NH2
• D. CH3

Explanation: order of activating group (NH2, NHR, NHCOCH3, OCH3,CH3,C2H5(and deactivating group (NO2, CN, CHO, COR, COOH, COOR, SO3H)to increase and…

• A. A cyclic compounds
• B. Ali cyclic compounds
• C. Hetro cyclic compounds
• D. Aromatic compounds

Explanation: Aromatic compounds are a class of cyclic organic compounds that contain one or more rings with a special stability due to the…

• A. R
• B. OH
• C. COR
• D. NH2

Explanation: The acyl group (COR) is not ortho para directing and activating. It is a deactivating group due to the presence of the carbonyl group…

• A. -OH
• B. -OR
• C. -NH2
• D. -CN

Explanation: -CN (Cyano group) is a deactivating group. It withdraws electron density from the ring through the inductive effect, reducing the…

• A. of its cyclic nature
• B. of having three double bonds
• C. of aromatic character
• D. of delocalization of electrons

Explanation: The correct answer is that benzene undergoes substitution reactions more easily due to the delocalization of electrons.

• A. An aromatic compound cannot be completely converted into CO2 and other products during burning
• B. The available amount of oxygen present in the air is not sufficient to completely burn the available compound
• C. Aromatic compounds produce compounds on burning that are of black color
• D. None of the above

Explanation: Aromatic compounds produce a smoky flame when burned due to their high carbon content.

• A. slower rate
• B. faster rate
• C. same rate
• D. depends on the conditions

Explanation: Compared to benzene, nitration of toluene occurs at a faster rate due to the presence of the methyl group (-CH3), which is an…

• A. PVC
• B. Benzene
• C. Toluene
• D. Teflon

Explanation: Benzene is formed by the cyclic trimerization of three ethyne (acetylene) molecules in a chemical process that rearranges the atoms into a…

• A. They have ring structure of carbon atoms.
• B. They have a relatively high percentage of hydrogen atoms.
• C. They have a relatively high percentage of carbon atoms.
• D. They resist reactions with air/oxygen.

Explanation: The aromatic compound displays aromaticity. They burn with a strong sooty yellow flame.

• A. -R
• B. -COR
• C. -NH2
• D. NR2

Explanation: Ortho and para directing grps release electrons to the benzene ring increasing the chemical reactivity of the benzene ring towards…

• A. Chlorobenzene
• B. Acetophenone
• C. Benzoic acid
• D. Benzophenone

Explanation: The reaction between benzene and acetyl chloride in the presence of lewis acid results in the formation of an aryl ketone , methyl phenyl…

• A. Benzene
• B. Toluene
• C. O-Xylene
• D. Metaxylene

Explanation: Acetylene on passing through a red hot iron tube undergoes cyclic polymerization.

• A. -OH
• B. -NH2
• C. -Cl
• D. -OCH3

Explanation: In electrophilic aromatic substitution, the nature of the substituent on the benzene ring plays a crucial role in determining the position…

• A. Benzene
• B. Toluene
• C. Benzoic acid
• D. Nitrobenzene

Explanation: The correct answer is Toluene. Toluene undergoes nitration much faster than benzene due to the presence of a methyl group.

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Cresol is a derivative of benzene that has a methyl group CH3 and a phenol group OH attached to the benzene ring.Ortho-Cresol, also called…

• A. -OH
• B. -NR2
• C. -CN
• D. -OR

Explanation: The correct answer is -CN. The -CN group is a meta-directing group because it withdraws electron density from the benzene ring…

• A. -NH4+
• B. -NH3
• C. -C≡N
• D. -COR

Explanation: Activating groups are Atoms or groups that make the benzene molecule more reactive by increasing the ring's electron density.The resonance…