All Free Chemistry MCQs with Answers

• A. identification of elements
• B. Estimation of amounts of elements
• C. Molar ratio of elements
• D. Molar volume of elements

Explanation: Qualitative analysis is a branch of analytical chemistry that is concerned with identifying the elements or compounds present in a sample.

• A. mass of an atom itself is in fraction
• B. atomic masses are average masses of isobars
• C. atomic masses are average masses of isotopes proportional to their relative abundance
• D. atomic masses are average masses of isotopes

Explanation: Most elements exist as a mixture of isotopes, each with a slightly different mass due to variations in the number of neutrons.

• A. properties which depend upon mass
• B. The arrangement of electrons in orbitals
• C. chemical properties
• D. All of the above

Explanation: Isotopes of an element have the same number of protons (same atomic number), which means they belong to the same chemical element and have…

• A. Sand
• B. Hemoglobin
• C. Diamond
• D. Maltose

Explanation: A macromolecule is a large, complex molecule typically formed by the polymerization of smaller subunits. Sand is not a macromolecule.

• A. Combustion method
• B. Duma's method
• C. Kjeldahl's method
• D. All of the above methods are for different purposes

Explanation: The combustion method is a commonly used technique to estimate the percentage of carbon and hydrogen in an organic compound.

• A. High energy electron beam
• B. ∝-particle
• C. X-rays
• D. All of the above

Explanation: Molecular ions are formed by passing high energy electron beam, X-rays or α-particles: Passing a high-energy electron beam through a…

• A. sea water
• B. brass
• C. tape water
• D. graphite

Explanation: A substance is defined as matter that has a specific composition and distinct properties.Graphite - Graphite is a form of carbon.

• A. Are always different
• B. Are always similar
• C. May be similar or different
• D. Ionic compound do not have any empirical formula

Explanation: The relationship between the empirical formula and formula unit of an ionic compound depends on the individual compound and its structure.

• A. 1.2 x 10 23
• B. 6 x 10^22
• C. 6 x 10^2
• D. 12 x 10^2

Explanation: To determine the number of oxygen atoms in a given mass of carbon dioxide (CO2 ), you can use the following steps:Find the moles of CO2…

• A. 3.6g of water
• B. 4.4g of C2H5OH
• C. 2.8g of CO
• D. 5.4g of N2O2

Explanation: To find the largest number of molecules, we need to calculate the number of moles for each substance.

• A. 0.32g
• B. 0.64g
• C. 0.16g
• D. 0.96

Explanation: Here's how to find the weight of liquefied oxygen:Convert volume to moles:○ We need to convert the volume of oxygen from milliliters (mL)…

• A. 1.008g of H has 6.02 x 10^23 atoms
• B. 2.016g of H2 has 2 x 6.02 x 10^23 atoms
• C. 1.008g of H2 has 6.02 x 10^23 atoms
• D. Both Options A and B are correct

Explanation: 1 mole of any substance contains Avogadro's number of particles, which is approximately 6.02 x 10^23.The molar mass of H2 (molecular…

• A. 6.022 x 10²³ / 1.0 x 10⁻⁶
• B. 1.0 x 10⁻⁶ x 6.022 x 10²³ / 20.2
• C. 1.0 x 10⁻⁶ x 6.022 x 10²³
• D. 1.0 x 10⁻⁶ x 6.022 x 10²³ / 9.65 x 10⁴

Explanation: To ionize each Ne atom to a Ne⁺ ion, one electron is removed per atom. Therefore, the total number of electrons to remove is equal to the…

• A. CH₂O
• B. C₂H₄O₂
• C. C₆H₁₂O₆
• D. C₃H₆O₃

Explanation: A molecule of glucose contains 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms.

• A. Ionic bond
• B. Hydrogen bond
• C. Covalent bond
• D. None of these options are correct

Explanation: Covalent bonding has a characteristic feature which involves the sharing of electrons between two non-metal atoms.

• A. Chemically similar
• B. Physically dissimilar
• C. Chemically dissimilar
• D. Both Options A and B are correct

Explanation: As the atomic number of different isotopes of an element is the same, they have the same electronic configuration hence they will show the…

• A. Chlorine molecules in 35.5g of chlorine gas
• B. Electrons in 1g of Hydrogen gas
• C. Hydrogen ions in 1 dm3 of 1 moldm-3 aqueous sulphuric acid
• D. Oxygen atoms in 22.4 dm3 of oxygen gas at STP

Explanation: 1g Hydrogen is equal to one-mole hydrogen atom and each atom of hydrogen contains one electron so there will be one-mole electron.

• A. 0.08
• B. 0.80
• C. 80
• D. 1280

Explanation: Mol of oxygen = given particles/ avagadros number = 1.5 x 1022 /6.02 x 1023 = 0.025 molmass= mole x molar mass of O20.025 x 32= 0.80g

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: Option B is correct.we know that No. of electron=n*NA =1.0*10-6*6.02*1023

• A. 2x6.022 x 10^23 atoms
• B. 2 x 10^23 atoms
• C. 35.5 x 6.022 x 10^23 atoms
• D. 2x6.02 x 10^22 atoms

Explanation: Number of atoms = n X NANo. of CI atoms = 2 x 6.02x1023