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 570 of 686
- A. NaCl(aq)
- B. NaCI(molten)
- C. NaCl(s)
- D. Silver metal
Explanation: The correct answer is C) NaCl(s). Solid sodium chloride (table salt) is not a conductor of electricity because its ions are not free to…
Correct answer: NaCl(s)- A. It involves conversion of electrical energy into chemical energy
- B. Anode has negative charge and cathode has positive charge in this cell
- C. It is reverse of addition reaction
- D. It is endothermic process
Explanation: The correct answer is B) Anode has a negative charge, and cathode has a positive charge in this cell.
Correct answer: Anode has negative charge and cathode has positive charge in this cell- A. A
- B. B
- C. C
- D. D
Explanation: The correct answer is A) Option A presents the correct decreasing order of discharge of positive ions at the cathode based on the…
Correct answer: A- A. Na reacts with water
- B. Na+ is more stable than Na atom
- C. Na+ reacts with CI ion in the solution
- D. Reduction of H2O is preferred to Na+
Explanation: This option is the correct reason why Na metal cannot be produced by electrolysis of an aqueous solution of NaCl.
Correct answer: Reduction of H2O is preferred to Na+- A. A
- B. B
- C. C
- D. D
Explanation: To act as an oxidizing agent the hydrogen itself has to be reduced. The oxidation number of hydrogen in H2 is 0 and in NaH is -1, it is…
Correct answer: C- A. 9
- B. 6
- C. 3
- D. 2
Explanation: In an acidic medium Cr is reduced from +6 to +3 as: Cr2O7-2+ 14H+ +6e- → 2Cr+3 + 7H2O and Fe2+ is oxidized to Fe3+ as: Fe2+→ Fe3++ e- So…
Correct answer: 6- A. The smaller the E°red, the greater the reducing power of a metal
- B. E°rcd of Li1 is minimum (-3.04V)
- C. The greater the E°red, the greater the oxidizing power of a non-metal
- D. E°red of Cl2 is maximum (+2.87V)
Explanation: The statement that E°red of Cl2 is maximum (+2.87V) is incorrect. Chlorine has a high E°red because it is a strong oxidizing agent.
Correct answer: E°red of Cl2 is maximum (+2.87V)- A. It is used as a reference electrode
- B. its E°red is zero or less than zero
- C. When it is connected to zinc electrode in a galvanic cell, it act as cathode
- D. When it is connected to Cu electrode in a galvanic cell, it act as anode
Explanation: The standard reduction potential (E°red) of the standard hydrogen electrode is defined to be exactly 0 volts. It cannot be less than zero.
Correct answer: its E°red is zero or less than zero- A. Na is deposited
- B. O2 gas is released
- C. Neither Na or H2 is released
- D. H2 gas is released
Explanation: On the electrolysis of aqueous solution of Na2SO4 by using inert electrodes, hydrogen gas is released at the cathode electrode.The reason…
Correct answer: H2 gas is released- A. H2gas is released
- B. O2 gas is released
- C. SO2 gas is released
- D. Neither O2 or SO2 gas is released
Explanation: On the electrolysis of dilute H2SO4 solution by using inert electrodes, oxygen gas is released at the anode electrode.The reason for this…
Correct answer: O2 gas is released- A. Net charge should be same on each side
- B. Total number of atoms should be same
- C. Total number of ions should be same
- D. Both A and B
Explanation: Ion-Electron Method (Half-Reaction Method): The ion-electron method, also known as the half-reaction method, is a technique used to…
Correct answer: Both A and B- A. Graphite
- B. Copper
- C. Iron
- D. Inert materia
Explanation: In Down's cell, which is used for the electrolytic production of sodium metal, the cathode is made up of iron.In the Down's cell, the…
Correct answer: Iron- A. Aqueous NaCI
- B. Aqueous NaNO3
- C. Fused NaCI
- D. Fused NaNO3
Explanation: Down's cell is used for the electrolysis of molten sodium chloride (NaCl) to produce sodium metal and chlorine gas.
Correct answer: Fused NaCI- A. An Acid
- B. A base
- C. Its own ions
- D. Water
Explanation: When a metal is dipped into a solution containing its own ions (in the form of a salt), electrode potential can be developed.
Correct answer: Its own ions- A. Buffer
- B. Spectator substance
- C. Reaction intermediate
- D. None of these
Explanation: An intermediate is a species which appears in the mechanism of a reaction, but not in the overall balanced equation.
Correct answer: Reaction intermediate- A. E
- B. E-1
- C. E°
- D. ∂
Explanation: In electrochemistry the electrode potential is the electromotive force of a cell built of two electrodes. It is denoted by the sign E.
Correct answer: E°11397. Number of electron added on both sides of oxidation and reduction half reactions are balanced:
- A. At the start of procedure
- B. Somewhere in the middle of balancing
- C. After Adding two half reactions
- D. Before Adding two half reactions
Explanation: For the reduction half, there are 12 positive charges on the left side of the equation and 6 positive charges on the right side of the…
Correct answer: Before Adding two half reactions- A. Just to be sure, I called three more doctors' offices.
- B. Just to be sure, I called three more doctors offices.
- C. Just to be sure, I called three more doctor's' offices.
- D. Just to be sure, I called three more doctor offices.
Explanation: This option is correct. It uses a comma correctly after the introductory phrase "Just to be sure." Additionally, "doctors' offices" is the…
Correct answer: Just to be sure, I called three more doctors' offices.- A. [Ar] 3d44s1
- B. [Ar] 3d44s2
- C. [Ar] 3d54s2
- D. [Ar] 3d54s1
Explanation: In 3d series (1st series of transition elements), two elements "Cr" and "Cu" have differe electronic configuration.
Correct answer: [Ar] 3d54s1- A. [Ar]4s23d4
- B. [Ar) 4s23d4
- C. [Ar]3d54s1
- D. [Ar)4s13d6
Explanation: The correct electronic configuration of Chromium (Cr) is 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵.
Correct answer: [Ar]3d54s1