All Free Chemistry MCQs with Answers

• A. Below 5
• B. 7
• C. Between 5 and 7
• D. Between 7 and 14

Explanation: It results from high levels of atmospheric nitric and sulfuric acids that get washed down to earth.

• A. 10-50
• B. 50-60
• C. 5-30
• D. 10-80

Explanation: 10-50 km: This option is the correct answer. The ozone layer is a layer of the Earth's atmosphere that extends approximately 10-50 km…

• A. Ultraviolet
• B. Indigo
• C. Infra-Red
• D. Green

Explanation: Infra-Red: This option is the correct answer. Light rays from the sun, including visible and ultraviolet light, can be absorbed by CO2 in…

• A. CFCs
• B. CO2 and CO
• C. HCL and Oxides of Nitrogen
• D. SO2 and Oxides of Nitrogen

Explanation: SO2 and Oxides of Nitrogen: This option is the correct answer. Sulfur dioxide (SO2) and nitrogen oxides (NOx) are the main gases produced…

• A. SiO2
• B. CO2
• C. SO3
• D. Al2O3

Explanation: SO3 reacts with rain water to form H2SO4 (sulfuric acid) which is a major source of acid rain.

• A. Cl-Cl
• B. Cl-F
• C. C-Cl
• D. C-F

Explanation: The Cl-F bond is less stronger than the C-Halide bond as it can be broken down by sunlight or UV radiation.

• A. Chlorofluorocarbons
• B. Carbon tetrachlorie
• C. Methane
• D. Hydroflorocarbons

Explanation: Factual recall.Chlorofluorocarbons (CFCs) have a significant effect on the ozone layer.

• A. NO2-
• B. HNO2
• C. NO3-
• D. NO2+

Explanation: Explanation:During the nitration of benzene which is an electrophilic substitution reaction, the active nitrating agent is NO2+.

• A. Alkyl group
• B. Phenyl group
• C. Benzyl group
• D. Methyl group

Explanation: A is incorrect as alkyl group is formed when one hydrogen is removed from an alkane chain;not a benzene ring.B is correct as when one…

• A. Conc. HNO3 and conc. HCl
• B. Conc. HNO3 and conc. Acetic acid
• C. Conc. HNO3 and H3PO4
• D. Conc. HNO3 and conc. H2SO4

Explanation: A is incorrect as these reactants are not used in nitration.B is incorrect as these reactants are not used in nitration.C is incorrect as…

• A. Acetyl chloride
• B. Acetic acid
• C. Ethyl benzene
• D. Ethanoic acid

Explanation: The benzene reacts with acetyl chloride in presence of anhydrous aluminum chloride to form acetophenone.

• A. Nitration
• B. Ammonolysis
• C. Sulphonation
• D. Reduction of benzene

Explanation: Nitration reactions are the addition of a nitro group into an organic compound.

• A. Acylation
• B. Carbonyl reduction
• C. Alkylation
• D. Formylation

Explanation: The introduction of an RC(O)+ group (also called an acyl group) in benzene is called acylation.

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

Explanation: We are asked to describe the possible product of bromination. From the question, we can possibly conclude that the OH group is already…

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

Explanation: This set of reaction is known as Friedal Craft Acylation and in this, CH3CH3COCl i.e propanoyl chloride reacts with benzene and the…

• A. ii, iii, iv
• B. ii, iii
• C. i, iv
• D. i, ii, iv

Explanation: The 3 5 directing groups or Meta directing groups are as follows:Aldehyde (-CHO), Ketone (-CO-), Ester (-RCOOR'), Carboxyl Group (-COOH)…

• A. CH3CO+
• B. AlCl3
• C. CH3+
• D. CH3COCl

Explanation: CH3COCl reacts with AlCl3 to form ----> AlCl4- and CH3CO+CH3CO+ has a positive charge thus it is an electrophile and attracted to…

• A. Electrophilic addition
• B. Electrophilic substitution
• C. Nucleophilic substitution
• D. Nucleophilic addition

Explanation: Benzene has an extended delocalised pi system above and below the ring which makes it highly attracted to electron-deficient species…

• A. Br+
• B. FeCl4+
• C. Fe2+
• D. Fe3+

Explanation: Benzene reacts with bromine in an electrophilic substitution reaction, but only in the presence of a catalyst to yield bromobenzene.

• A. Benzoic acid
• B. Methyl benzene
• C. Benzaldehyde
• D. Nitrobenzene

Explanation: Activating groups increase the reactivity of electrophilic substitutions, whereas deactivating groups decrease it.Activating groups are…