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 620 of 686
- A. 32g
- B. 24g
- C. 16g
- D. 8g
Explanation: Explanation for this question will be added soon.
Correct answer: 8g- A. 6.22 x 10^23 atoms of U-235
- B. 6.22 x 10^23 atoms of U-238
- C. 6.22 x 10^23 atoms of U-234
- D. All of these options are correct
Explanation: There are three naturally occurring isotopes of uranium: uranium-238, the heaviest and most abundant, uranium-235 and uranium-234.
Correct answer: 6.22 x 10^23 atoms of U-238- A. 1.8mg
- B. 0.184mg
- C. 0.55mg
- D. 0.64mg
Explanation: We know that:Mass of an electron = 9.1 ×10-³¹Avogadro's constant = 6.02 ×10²³Mass of one mole Electron: = 9.1 × 10-³¹ × 6.02 × 10²³ = 5.48…
Correct answer: 0.55mg- A. Shape
- B. Size
- C. Molecularity
- D. Atomicity
Explanation: OPTION A: The shape of a molecule determines its geometry. OPTION B: The size of a molecule tells us how small or big it is.
Correct answer: Atomicity- A. 24 NA
- B. 2 NA
- C. 20 NA
- D. 1 NA
Explanation: The atomic number of magnesium is 12. Mg+2 means it has lost 2 electrons. Therefore, In the Mg+2 ion, there are 12-2 = 10 electrons. No.
Correct answer: 20 NA- A. 0.1, 0.2
- B. 0.1, 0.3
- C. 0.2, 0.4
- D. 0.2, 0.1
Explanation: d) 0.2 moles of hydrogen ions (H+) and 0.1 mole of sulfate ions (SO4^2-):Using the same calculation as above, we get:Moles of H+ ions ≈…
Correct answer: 0.2, 0.1- A. 8g of oxygen
- B. 16g of oxygen
- C. 32g of oxygen
- D. 24g of oxygen
Explanation: Option D is the right answerSolution number of moles of Al = given mass/molar mass=27/27= 1 moleThe balance equation for such reaction…
Correct answer: 24g of oxygen- A. Mass
- B. Volume
- C. Moles
- D. All of these options are correct
Explanation: If we are given the mass of a substance, we can calculate the mass, volume, and moles of the other substance with the help of a balanced…
Correct answer: All of these options are correct- A. 1
- B. 2
- C. 3
- D. 4
Explanation: Correct option is B. A molecule of water has two bonds so 1 mole of water will contain 2 mole of bonds.
Correct answer: 2- A. Qualitative
- B. Quantitative
- C. Both A & B
- D. Extensive
Explanation: Both qualitative and quantitative analysis were used in the 17th century to study the composition of pure substances.
Correct answer: Quantitative- A. One million
- B. Two million
- C. One billion
- D. Two billion
Explanation: 'Fullstops' contain millions of atoms, substantiating how small atoms are, to an extent where millions can fit in a small dot, placed…
Correct answer: Two million- A. 1-Ethyl-3, 4 - dimethylcycloheptane
- B. 2-Ethyl-4, 5-dimethylcyclohexane
- C. 1-Ethyl - 4, 4-dimethylcyclohexane
- D. 4-Ethyl-1, 2 - dimethylcyclohexane
Explanation: Apply rules of nomenclature. The adjacent methyl groups will be preffered first because they are closer compared to ethyl and methyl groups.
Correct answer: 4-Ethyl-1, 2 - dimethylcyclohexane- A. Ethyl chloride
- B. Ethene chlorine
- C. Chiaro ethane
- D. Vinyl chloride
Explanation: The compound shown is Vinyl Chloride, which is an organochloride with the formula H₂C=CHCl.
Correct answer: Vinyl chloride- A. CH3Cl
- B. CH2Cl2
- C. CHCl3
- D. CH2Cl
Explanation: Chloroform or trichloromethane is an organic compound which has a molecular formula CHCl3. The answer is C.
Correct answer: CHCl3- A. Carbon
- B. Magnesium
- C. Halogen
- D. None of the above
Explanation: The explanation for this question will be added soon.
Correct answer: Magnesium- A. Beta hydroxy carboxylic acids
- B. Alpha hydroxy carboxylic acids
- C. Carboxylic acids
- D. Unsaturated acids
Explanation: The hydrolysis of cyanohydrin gives alpha hydroxy, carboxylic acids. In the above reaction, the cyano group is hydrolyzed to a carboxylic…
Correct answer: Alpha hydroxy carboxylic acids- A. Acid.
- B. Base.
- C. Water.
- D. Both acid and base.
Explanation: Nucleophilic addition reactions of carbonyl compounds involve the addition of a nucleophile (an electron-rich species) to the carbon atom…
Correct answer: Both acid and base.- A. Elimination+ addition
- B. Elimination+ Substitution
- C. Addition + substitution
- D. None of these
Explanation: Condensation involves elimination and addition. It is a reaction in which a water molecule is produced as a by-product.
Correct answer: Elimination+ addition12399. In the addition of sodium bisulfite to carbonyl system, which of the following is a nucleophile?
- A. Sulphide ion
- B. Sulfite ion
- C. Hydride ion
- D. Sodium ion
Explanation: The addition of sodium bisulfite to a carbonyl group takes place as follows:Sodium bisulfite ionizes to form sulfite ions.The sulfite ion…
Correct answer: Sulfite ion- A. Hydroxyl ion
- B. Carbocation
- C. Carbanion
- D. Water
Explanation: The reaction mechanism below shows that the carbanion is the nucleophile of the reaction:
Correct answer: Carbanion