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 569 of 686
- A. H2O is the reducing agent
- B. H2O is the oxidising agent
- C. Carbon is the oxidising agent
- D. Oxidation-reaction does not occur
Explanation: In the given reaction, H2O is reduced to H2, meaning it gains hydrogen atoms.
Correct answer: H2O is the oxidising agent- A. Cu + HNO3 → Cu(NO3)2 + NO + H2O
- B. I2 + OH- → IO- + I- + H2O
- C. Cl2 + I2 → 2ClI
- D. Zn + 2HCl → ZnCl2 + H2
Explanation: In a disproportionation reaction, a single element in one oxidation state is simultaneously oxidized and reduced to form two different…
Correct answer: I2 + OH- → IO- + I- + H2O- A. A
- B. B
- C. C
- D. D
Explanation: Cu + H2SO4 → CuO + H2O + SO2 (H2SO4 act as oxidant) CuO + H2SO4 → CuSO4 + H2O (H2SO4 act as acid)
Correct answer: C- A. Both half-cell reactions take place simultaneously
- B. Of resistance of the wire
- C. A reaction does not take place on its own
- D. None of the above
Explanation: It is impossible to measure the actual voltage of any half-cell by itself because a reaction does not take place on its own.
Correct answer: A reaction does not take place on its own- A. 4.305 amp
- B. 17.22 amp
- C. 8.61 amp
- D. 2.1525 amp
Explanation: The correct answer is 8.61 amp. To determine this, we utilize Faraday's laws of electrolysis, which state that the amount of substance…
Correct answer: 8.61 amp- A. Less than anode
- B. The same as anode
- C. More than anode
- D. Always zero
Explanation: At cathode reduction takes place hence it has greater Eered than anode.
Correct answer: More than anode- A. A
- B. B
- C. C
- D. D
Explanation: The correct answer is Option C. Copper (Cu) is below hydrogen in the electrochemical series, which means it cannot displace hydrogen from…
Correct answer: C- A. A
- B. B
- C. C
- D. D
Explanation: The reaction MgO + 2H2O → MgCl2 + 2H2O is a double displacement reaction.
Correct answer: B- A. Anode
- B. Cathode
- C. At the surface of the electrolyte
- D. None of these
Explanation: In electrochemical cells, reduction occurs at the cathode, which is the electrode where electrons are gained by the chemical species.
Correct answer: Cathode- A. Option A
- B. Option B
- C. Option C
- D. Option D
Explanation: Following is the solution to this question:
Correct answer: Option B- A. VO2+ → V2O3
- B. Na → Na+
- C. CrO4-2 → Cr2O72-
- D. Zn2+ → Zn
Explanation: 2Cr6+ → Cr26+ ; Neither oxidation nor reduction.
Correct answer: CrO4-2 → Cr2O72-- A. The law is valid at infinite dilution
- B. The law is valid for weak electrolytes only
- C. The basis of law is independent migration of ions
- D. None of the above
Explanation: The law is valid for weak and strong electrolytes both.
Correct answer: The law is valid for weak electrolytes only- A. Zn(s)
- B. Cr(s)
- C. H2(g)
- D. Fe 2+(aq)
Explanation: Zn2+(aq) is having minimum reduction potential. So oxidation potential of Zn(s) will be maximum and it will be strongest reducing agent.
Correct answer: Zn(s)- A. 0.2 mole of 2 Cu+ will go into solution
- B. 560 ml O2 liberate
- C. No loss in weight
- D. 2 gram of copper goes into solution as Cu2+
Explanation: During electrolysis of CuSO4 solution using Cu electrodes, the cell reaction is: Anode: Cu (s) → Cu++ + 2e- Cathode: Cu++(aq) + 2e- →…
Correct answer: 2 gram of copper goes into solution as Cu2+- A. H2
- B. CI2
- C. O2
- D. Na
Explanation: For aqueous solution of NaCl at cathode.H2O is reduced to H2 as its Ered is higher than Na+. 2H2O + 2e- → H2 + 2OH-
Correct answer: H2- A. Electromotive force
- B. Electrode potential
- C. Cell potential
- D. Both A and C
Explanation: Emf or cell potential is the force used to drive electron in a circuit.
Correct answer: Both A and C- A. N
- B. F
- C. O
- D. CI
Explanation: Fluorine is very strong oxidizing agent and is at the bottom of ECS. Indicating its highest Eered= +2.87V.
Correct answer: F- A. H2
- B. CI2
- C. O2
- D. Na
Explanation: During electrolysis of brine, chlorine is obtained on anode.
Correct answer: CI2- A. It is apparent charge on an atom in a compound
- B. Its value is either zero, positive or negative
- C. It can be variable
- D. Xenon (Xe) can show maximum oxidation state +6 in its compounds
Explanation: Oxidation state or oxidation number, is the hypothetical charge of an atom if all of its bonds to other atoms were fully ionic.
Correct answer: Xenon (Xe) can show maximum oxidation state +6 in its compounds- A. They may be get deposited/released on the electrode surface
- B. They may go out in the form of gases
- C. Electrolytic material may get dissolved into the solution as ions
- D. In Nelson cell, Na metal is a primary product
Explanation: The correct answer is D) In Nelson cell, Na metal is a primary product.
Correct answer: In Nelson cell, Na metal is a primary product