All Free Chemistry MCQs with Answers
Every Chemistry question in the bank, across all chapters, each with the correct answer and a written explanation. Free and unlimited, with no account needed.
13,720 questions · page 657 of 686
- A. Nitrobenzene
- B. Benzoic acid
- C. Benzaldehyde
- D. Phenol
Explanation: Option "a) Nitrobenzene," "b) Benzoic acid," and "c) Benzaldehyde" do not have electron-donating groups like the hydroxyl group in phenol.
Correct answer: Phenol- A. m-nitro benzoic acid
- B. o-nitro benzene methanoic acid
- C. o-nitro benzoic acid
- D. None of the above
Explanation: When two functional groups are next to each other in a benzene ring, we call them ortho group or o-group.
Correct answer: o-nitro benzene methanoic acid- A. m-chloro nitrobenzene
- B. o-chloro nitrobenzene
- C. p-chloro nitrobenzene
- D. All of above
Explanation: When nitrobenzene and chlorine come together in the presence of AlCl3, they undergo a chemical reaction.
Correct answer: m-chloro nitrobenzene- A. Benzene
- B. 1,3 -Dinitrobenzene
- C. Nitrobutene
- D. 1,3,5 trinitrobenzene
Explanation: Benzene is reactive because of its delocalized pi electron system. This system of alternating double bonds makes benzene more stable than…
Correct answer: Benzene- A. 2nd group
- B. 4th group
- C. 3rd group
- D. 5th group
Explanation: The outer electronic configuration of element "X" is ns2 np2, indicating that it has 2 electrons in the s subshell and 2 electrons in the…
Correct answer: 4th group- A. s-block
- B. d-block
- C. f-block
- D. p-block
Explanation: In the periodic table, elements with similar properties are grouped in blocks based on their electronic configurations.
Correct answer: p-block- A. 3f
- B. 4f
- C. 5f
- D. 6f
Explanation: The lanthanides are characterized by their incompletely filled 4f sub-shells.
Correct answer: 4f13128. What happens to the molecule when its atoms are brought closer than the bond length between them?
- A. Molecule becomes unstable
- B. Molecule becomes more stable
- C. Molecule starts vibrating
- D. Stability of the molecule remains unchanged.
Explanation: Bond length is defined as the distance between two nuclei of atoms in a covalent bond.
Correct answer: Molecule becomes unstable- A. Atoms in the O2 molecules are held by a double bond
- B. 0-0 bonds are strong
- C. The amount of metal in the anode
- D. All of the above
Explanation: Atoms in an Oxygen molecule are held together by a double bond. O-O single bonds have a bond length of 1.48 angstrom, while O-O double…
Correct answer: Atoms in the O2 molecules are held by a double bond- A. Kept constant
- B. Zero
- C. Variable
- D. None of the above
Explanation: Its is kept constant. Imagine you have a balloon filled with gas. If you keep the temperature and the amount of gas inside the balloon…
Correct answer: Kept constant- A. 1/2
- B. 2x
- C. 4x
- D. 1/4
Explanation: Option B is correct. When the pressure of an ideal gas is reduced to half at a constant temperature, the volume of the gas will double.
Correct answer: 2x13132. Fizzy drinks contain dissolved CO2. The CO2 reacts with H2O to form weak acid which is called:
- A. Acetic acid
- B. Carbonic acid
- C. Lactic acid
- D. Formic acid
Explanation: The weak acid formed when CO2 reacts with water in fizzy drinks is called "Carbonic acid." Therefore, the correct option is "Carbonic…
Correct answer: Carbonic acid13133. Which is strongest acid?
- A. HClO
- B. HClO2
- C. HClO3
- D. HClO4
Explanation: HClO4 (perchloric acid): This acid is the strongest among the options. It is a highly corrosive and reactive acid.
Correct answer: HClO4- A. Base
- B. Acid
- C. Salt
- D. Basic anhydride
Explanation: Metallic oxides that are basic will react with water to form a basic solution.
Correct answer: Base13135. Acids are classified as monoprotic or polyprotic which of the following is a polyprotic acid?
- A. CH3CO2H (aq)
- B. HOCl (aq)
- C. HCHO2
- D. H2CO3
Explanation: H2CO3 is a polyprotic acid. It can donate two protons in separate dissociation reactions: H2CO3 ←→ H+ + HCO3- HCO3- ←→ H+ + CO32- These…
Correct answer: H2CO313136. A nucleophile is
- A. Lewis acid
- B. Bronsted acid
- C. Bronsted base
- D. Lewis base
Explanation: A nucleophile is a chemical species that donates an electron pair to form a new chemical bond.
Correct answer: Lewis base- A. HCO-
- B. CN-
- C. NO3-
- D. PO4-
Explanation: The HCO- ion can act as a Bronsted acid by donating a proton to a water molecule, forming H2CO3.
Correct answer: HCO-- A. CN-
- B. NH3
- C. CH3 - O - CH3
- D. I+
Explanation: The correct answer is I+. A Lewis acid is defined as an electron pair acceptor, and I+ fits this definition because of its positive charge…
Correct answer: I+- A. (CH3)3N
- B. PH3
- C. BF3
- D. O2
Explanation: The correct answer is BF3 because it is an electron-deficient molecule with the ability to accept electron pairs, making it a Lewis acid.
Correct answer: BF3- A. ROH> H2O> C6H5OH>RCOOH
- B. C6H5OH > H2O> ROH > RCOOH
- C. RCOOH > C6H5OH > H2O > ROH
- D. RCOOH > ROH > C6H5OH > H2O
Explanation: The increasing strength of acidities is as follows; carboxylic acids, phenols, water and then ethanol.
Correct answer: RCOOH > C6H5OH > H2O > ROH