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 670 of 686
- A. 178
- B. 34g
- C. 51g
- D. 40g
Explanation: 74g of Ca(OH)2 equals 1 mole since the molar mass is 74 g/mol. The dissociation of Ca(OH)2 produces 2 moles of OH ions for every mole of…
Correct answer: 34g- A. Definite proportion
- B. Multiple proportion
- C. Reciprocal proportion
- D. None of above
Explanation: The law of constant composition states that a given chemical compound always contains its component elements in fixed ratio (by mass) and…
Correct answer: Definite proportion- A. 5 x 6.02 x 10^23 atoms
- B. 30 x 6.02 x 10^23
- C. 3x x 6.02 x 10^23
- D. 6 x 6.02 x 10^23
Explanation: The number of atoms in one mole of substance can be calculated byNo. Of atoms = atomicity X Avogadro's no.As a molecule of Ca(OH)2…
Correct answer: 5 x 6.02 x 10^23 atoms- A. 17g
- B. 34g
- C. 51g
- D. 40g
Explanation: mole= given mass in gram/molar mass Mole of calcium hydroxide = 74/74 = 1 mole OH- mass in Ca(OH-)2 = (17)2 = 34 OH- ions = 1 x 34 = 34g…
Correct answer: 34g- A. 40L
- B. 30L
- C. 20L
- D. 10L
Explanation: The balanced chemical equation 𝐻2 + 𝐶𝑙2 = 2𝐻𝐶𝑙 shows that each mole of Cl2 produces two moles of HCl.
Correct answer: 20L- A. 4g of hydrogen
- B. 4g of magnesium
- C. 71 g of chlorine
- D. 127 g of iodine
Explanation: Now let's calculate the number of atoms for each substance: a) 4g of hydrogen (H): 4 moles of hydrogen × (6.022 × 1023 atoms/mol) = 2.409…
Correct answer: 71 g of chlorine- A. (5x63.55/76.55)/40x100
- B. 40/5x79.55/63.x100
- C. 5/40x79.55/63.55x100
- D. 25/40x100
Explanation: To find the percentage of copper (Cu) in the sample, we can use the formula:Percentage of Cu = (Mass of Cu / mass of sample) × 100Given…
Correct answer: (5x63.55/76.55)/40x100- A. 1.2L
- B. 22.4L
- C. 30.5L
- D. 44.8L
Explanation: To determine the volume of the gas at STP (Standard temperature pressure), we can use Avogadro's law, which states that equal volumes of…
Correct answer: 22.4L- A. 180g
- B. 81g
- C. 1.8g
- D. 0.18g
Explanation: The solution for this question is given below:
Correct answer: 1.8g- A. 6.022 × 10^23 amu
- B. 6.022 × 10^-23 amu
- C. 6.022 × 10^-24 amu
- D. 6.022 × 10^24 amu
Explanation: As 1 a.m.u is equal to 1.66 x 10^-24 g conversely 1 gram is equal to 6.022 x 10^23 amu.For example: 1 carbon atom = 12 amu 1 mole of…
Correct answer: 6.022 × 10^23 amu13391. One mole is the amount of substance that contains as many elementary entities as contained in:
- A. 0.12 kg of 6C12
- B. 1.2 kg of 6C12 atom
- C. 0.012 kg of 6C12 atom
- D. 0.12 kg of 8O16
Explanation: One mole is defined as the amount of substance containing as many elementary entities (atoms, molecules, etc.) as there are atoms in 12…
Correct answer: 0.012 kg of 6C12 atom- A. 0.20 x 3.01 x 10^23
- B. 0.20 x 2.016
- C. 0.70 x 6.02 x 10^23
- D. 1.008 x 6.02 x 10^23
Explanation: To find the number of molecules in 0.20 g of hydrogen gas, first recognize that hydrogen gas (H2) is diatomic.
Correct answer: 0.20 x 3.01 x 10^23- A. 0.0030 NA
- B. 0.25 NA
- C. 3.0 NA
- D. 4.0 N A
Explanation: The number of atoms in a sample can be determined by first calculating the number of moles using the formula: Number of moles = Mass /…
Correct answer: 0.25 NA- A. Avogadro's Law
- B. Graham's Law
- C. Dalton's Law
- D. Hund's Rule
Explanation: The correct answer is Avogadro's Law. This fundamental principle states that equal volumes of gases, at the same temperature and pressure…
Correct answer: Avogadro's Law- A. 3.0115 x 10^24
- B. 6.023 x 10^24
- C. 6.023 x 10^23
- D. 5.0 x 10^23
Explanation: 5 moles of water contains 5 moles of H2, therefore contains 10 moles of H atoms.The number of atoms in one mole of a substance is given by…
Correct answer: 6.023 x 10^2413396. How many oxygen atoms are present in 278g of Hydrated Ferrous Sulphate?(FeSO4.7Hz 0 = 278 any)
- A. 6.023 x 10^23
- B. 6.525 x 10^24
- C. 2.408 x 10^23
- D. 6.023 x 10^22
Explanation: The chemical formula for hydrated ferrous sulfate is FeSO4·7H2O, which includes 4 oxygen atoms from the sulfate ion (SO4) and 7 oxygen…
Correct answer: 6.525 x 10^2413397. 117.0g of NaCl have
- A. 12.04 x 10^23 Formula unit of NaCl
- B. 12.04 x 10^22 Formula unit of NaCl
- C. 12.04 x 10^23 Molecules of NaCl
- D. 6.023 x 10^23 Molecules of NaCl
Explanation: Option A is correct.To calculate the number of formula units of NaCl in 117.0g of NaCl, we can use the following steps: Calculate the…
Correct answer: 12.04 x 10^23 Formula unit of NaCl- A. 100g
- B. 150g
- C. 200g
- D. 300g
Explanation: Write the balanced chemical equation: CaCO3(s) -> CaO(s) + CO2(g)Calculate the moles of CO2:At STP, 1 mole of any gas occupies 22.4…
Correct answer: 200g- A. 6.023x10^22
- B. 6.023x10^21
- C. 6.023x10 ^23
- D. 4.02x10^23
Explanation: One mole of any substance contains 6.023 x 10^23 particles (atoms, molecules, or ions).
Correct answer: 6.023x10 ^23- A. 8 moles of O2
- B. 16 moles of H
- C. 2 molecules of CH
- D. One atom of Sulphur
Explanation: One molecule of oxygen (O2) has a molecular mass of approximately 32 atomic mass units (amu).
Correct answer: One atom of Sulphur