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 681 of 686
- A. CrOCl2
- B. COCl2
- C. CrO2Cl2
- D. CrCl6
Explanation: When a mixture of K2CR2O7 and metal chloride is added in warm conc: H2SO4 Chromyl chloride ( CrO2Cl2) which forms a deep reddish brown…
Correct answer: CrO2Cl2- A. 216
- B. 324
- C. 432
- D. 540
Explanation: Explanation for this question will be added soon.
Correct answer: 432- A. Option A
- B. Option B
- C. Option C
- D. None
Explanation: Kolbe's electrolysis method is a general method of preparation of substituted hydrocarbons from the substituted carboxylic acids by the…
Correct answer: Option A13604. Primary cells are used in calculators for long-service life the desirable quality of the cell is:
- A. Low energy densities
- B. No self discharge rates
- C. High self-discharge rates
- D. High energy densities
Explanation: A desirable quality of primary cells used in calculators is low or no self-discharge rates, meaning they retain their stored energy for…
Correct answer: No self discharge rates- A. Smelting
- B. Reasing
- C. Reduction
- D. Refining
Explanation: When metals are obtained from sulfide ores, the first step is typically smelting.
Correct answer: Smelting- A. Cathode
- B. Anode
- C. External conductor
- D. Cathode and anode
Explanation: In a Galvanic cell, the redox reaction occurs at two different electrodes, the cathode, and the anode.
Correct answer: Anode- A. that is required for the preparation of bleaching powder
- B. site free when excess of sulphuric acid is added to the bleaching powder
- C. that is required for the generation of hypochlorine
- D. Both B and C
Explanation: The bleaching action of bleaching powder is due to the release of "available chlorine" when it comes into contact with an acidic…
Correct answer: that is required for the generation of hypochlorine- A. Zn + Cu2+ → Zn2+ + Cu
- B. Zn2+ + Cu → Cu2+ + Zn
- C. 2 Fe(OH)3 → 2 Fe + 3/2 O2 + 3 H2O
- D. 2NaCl → 2Na + Cl2
Explanation: A spontaneous chemical reaction is one that occurs without continuous external energy input, often characterized by a negative Gibbs free…
Correct answer: Zn + Cu2+ → Zn2+ + Cu13609. Which of the following titrants would most likely be used as ths' own indicator in acid medium?
- A. K2Cr2O7 (Potassium dichromate)
- B. Iodine (I2)
- C. KMnO4 (Potassium permanganate)
- D. H2O2 (Hydrogen peroxide)
Explanation: Potassium permanganate (KMnO4) is used as its own indicator because it changes color distinctly at the endpoint of a titration in an…
Correct answer: KMnO4 (Potassium permanganate)- A. Cu only
- B. Zn only
- C. Cu & Ni only
- D. Ni and Zn only
Explanation: The correct answer is Zn only. Zinc has a standard reduction potential of -0.76 V, which is more negative than iron's -0.41 V.
Correct answer: Zn only- A. Pb is converted to PbO2
- B. PbSO4 is converted to Ph
- C. Pb is converted to PbSO4
- D. None of the above
Explanation: Pb oxidized to PBSO4When the battery is discharging, it acts as a galvanic cell and the following chemical reaction occurs:Negative:Pb(s)…
Correct answer: Pb is converted to PbSO4- A. Lead
- B. Lead oxide
- C. Lead hydroxide
- D. None of the above
Explanation: In a lead storage battery, the cathode is made up of lead dioxide, alternatively we can also use lead oxide as it is still an oxide of…
Correct answer: Lead oxide- A. Chloride is oxidized and sodium is reduced
- B. Chlorine acts as an oxidizing agent and sodium as a reducing agent
- C. Chlorine acts as a reducing agent
- D. None of the above
Explanation: In the reaction 2Na(s) + Cl2(g) ⟶ 2NaCl(s), sodium (Na) is oxidized to Na+, losing electrons, and thus acts as the reducing agent.
Correct answer: Chlorine acts as an oxidizing agent and sodium as a reducing agent13614. If one Faraday was to be 30,230 coulombs instead of 96,500 coulombs then charge on an electron is:
- A. 1.5 x 10^-19C
- B. 1 x 10^-19C
- C. 0.5 x 10^-19C
- D. 6.02 x 10^-19C
Explanation: The correct answer is 0.5 x 10-19C. A Faraday represents the total charge of one mole of electrons.
Correct answer: 0.5 x 10^-19C- A. Zn + Cu²+ → Zn²+ + Cu
- B. Fe + H2O → Fe2+ + OH-
- C. 2H2 + O2 → 2H2O
- D. Ag+ + Cl- → AgCl
Explanation: The correct answer is the reaction Zn + Cu²+ → Zn²+ + Cu. This reaction is spontaneous because it has a positive standard cell potential…
Correct answer: Zn + Cu²+ → Zn²+ + Cu- A. Corrosion cannot be eliminated completely
- B. Employing modern techniques corrosion can be completely eliminates.
- C. Corrosion process can be slowed down by certain methods.
- D. The presence of acidic oxide in the environment can accelerate the process of corrosion.
Explanation: Option B is correct as corrosion can be eliminated using modern techniques
Correct answer: Employing modern techniques corrosion can be completely eliminates.- A. BO2-
- B. SnO32
- C. S2O34-
- D. MnO42-
Explanation: It is a fact and has to be learntThe correct answer is D) MnO42-.MnO42- is unstable in solution because it can disproportionate to form…
Correct answer: MnO42-- A. Cathode rays
- B. X rays
- C. Anode rays
- D. All of the above
Explanation: cathode rays are not directly related to reducing effects. Cathode rays are streams of electrons that are emitted from the cathode…
Correct answer: Cathode rays- A. Oxidizing agent
- B. Reducing agent
- C. Bleaching agent
- D. Dehydrating agent
Explanation: Potassium dichromate (K2Cr2O7) is a strong oxidizing agent. It readily accepts electrons from other substances, causing them to be…
Correct answer: Oxidizing agent- A. remains constant
- B. increase
- C. decrease
- D. varies
Explanation: When the pressure of a gaseous mixture in equilibrium increases at constant temperature, the equilibrium constant remains constant.
Correct answer: remains constant