All Free Chemistry MCQs with Answers

• A. Water
• B. Cup
• C. Whole table
• D. All of these

Explanation: In the given situation, if the focus is on the water in the cup, then the system would be the water itself.

• A. System
• B. Surroundings
• C. Boundary
• D. None of these are correct

Explanation: A piston in a cylinder is part of the surrounding.

• A. Analyte
• B. System
• C. Surrounding
• D. Boundary

Explanation: In thermodynamics, a system refers to the part of the universe that is being studied or analyzed.

• A. 10
• B. 13
• C. 11
• D. 12

Explanation: Nitrogen has configuration 1s2 2s2 2p3. ( 5 valence electrons) Oxygen has configuration 1s2 2s2 2p4.

• A. Hexagonal
• B. Square planar
• C. Trigonal bipyramidal
• D. Tetrahedral

Explanation: d) Tetrahedral:The tetrahedral shape refers to a molecule with a central atom surrounded by four ligands, arranged at the corners of a…

• A. SnCl4
• B. NF3
• C. SO3
• D. H2O

Explanation: The molecule has a trigonal pyramidal structure, like ammonia. The bond angle is reduced from 107° in ammonia to 101.9° in NF3, because…

• A. Formation of NH4Cl , NHCl2 , NCl3 which are eye irritants
• B. Increased risk of bladder and rectal cancer by drinking water
• C. Offensive odour and taste due to chlorinated phenols.
• D. All of the above

Explanation: Disadvantages as advised by CDC guidelines for chlorinated water include following: The drawbacks of chlorination are: Relatively low…

• A. 10-4 K
• B. 10-2 K
• C. 10-1 K
• D. 10-5 K

Explanation: Explanation:Current attempts have resulted in temperature as low as 10-5 K. Hence, the correct answer is D.

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

Explanation: The activation energy is the lowest in Option C, hence it would be the most rapid reaction among the other options.

• A. Water
• B. Oxygen
• C. Carbon dioxide
• D. Sulfur dioxide

Explanation: Ethanol fermentation, also called alcoholic fermentation, is a biological process that converts sugars such as glucose, fructose, and…

• A. O - H
• B. C - O
• C. Both A and B
• D. None of these

Explanation: Which bond breaks depends on the nature of the attacking reagent. If a nucleophile attacks C-O bond will break, and if an electrophile…

• A. ZnO + CoO2
• B. ZnO + CuO
• C. ZnO + Ag2O
• D. Cr2O3 + ZnO

Explanation: A is incorrect as CoO2 is not used as a catalyst in the preparation of methanol.B is incorrect as CuO2 is not used as a catalyst in the…

• A. ZnCl2
• B. ThO2
• C. C6H5N
• D. Cr2O3

Explanation: A is incorrect as ZnCl2 is used as a catalyst in Lucas Test.Lucas test: a test that is Designed to Differentiate and Categorize Primary…

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

Explanation: Carbon atom that carries the -OH group is attached to two alkyl groups.

• A. Oxidation
• B. Fermentation
• C. Hydration
• D. Hydrogenation

Explanation: Ethanol can be oxidized to ethanoic acid by using oxidizing agents such as potassium permanganate (KMnO4), chromium trioxide (CrO3) or…

• A. Secondary alcohol
• B. Primary alcohol
• C. Tertiary alcohol
• D. Carboxylic acid

Explanation: A tertiary alcohol has the hydroxyl group on a carbon atom, which is bonded to two other carbon atoms.

• A. Alcohol is reduced
• B. O-H bond in ethanoic acid is broken
• C. O-H bond in ethanol is broken
• D. Acid is oxidised

Explanation: In the given reaction, ethanol and ethanoic acid react in the presence of a strong acid catalyst (usually concentrated sulphuric acid) to…

• A. Alkenes
• B. Alkynes
• C. Alkyl halides
• D. Ketones

Explanation: When secondary alcohols are oxidized with Na2Cr2O7 in the presence of H2SO4, they are converted to ketones.

• A. A
• B. B
• C. C
• D. D

Explanation: When CH3-CH2-OH is oxidized in the presence of K2Cr2O7 and H2SO4, the product formed is ethanal (acetaldehyde), which can further oxidize…

• A. C2H5Cl only
• B. C2H5Cl and HCl
• C. C2H5Cl, POCl3 and HCl
• D. C2H5Cl and POCl3

Explanation: When ethanol (C2H5OH) reacts with phosphorus pentachloride (PCl5), it undergoes a substitution reaction where the hydroxyl group (-OH) is…