All Free Chemistry MCQs with Answers

• A. Fractional Order
• B. Pseudo First Order
• C. First Order
• D. Second Order

Explanation: Explanation:The reaction is pseudo first order. Water is in excess as it is the solvent as a result will not affect the reaction order.

• A. Concentration of the product
• B. Concentration of the reactant
• C. Temperature of the reaction
• D. Surface area of the product

Explanation: In zero-order reactions, the rate is independent of the concentration of the reactants.

• A. Nitrous oxide
• B. Nitric oxide
• C. Nitrogen peroxide
• D. Nitrous anhydride

Explanation: Nitric oxide =+2Nitrous oxide = +1Nitrous anhydride= +3Nitrogen peroxide= +5

• A. ±2
• B. +4 and +6
• C. None of these
• D. Both A and B

Explanation: In H₂SO₄, the oxidation number of S is +6.In H₂SO₃, the oxidation number of S is +4.In Na₂S₂O₃, the oxidation number of S is +2.

• A. Redox Potential
• B. Oxidation Potential
• C. EMF of the cell
• D. Reduction Potential

Explanation: A stronger oxidizing agent means it undergoes reduction more easily and thus has greater standard reduction potential.

• A. Reducing agent
• B. Excellent precipitating reagent
• C. Germicide
• D. Oxidizing agent

Explanation: A is incorrect as KMnO4 isnt a reducing agent.B is incorrect as KMnO4 isnt a precipitating agent.C is incorrect as KMnO4 isnt used in…

• A. -8
• B. +8
• C. -6
• D. +6

Explanation: The oxidation of sulphur is 6+:it is because the oxide ion has a charge of -2 making it -8 overall, for four oxide ions.

• A. 5+
• B. 2+
• C. 3+
• D. 3-

Explanation: NO3N = xO = - 2x + (-2) × 3 = - 1x + (- 6) = - 1x - 6 = - 1x = - 1 + 6x = 5

• A. -1, +1
• B. -1, +3
• C. -1, +5
• D. +1, +5

Explanation: In NaCl, Na has an oxidation state of +1 so Cl is -1 and in NaClO3, Na is +1 and O is -6 while Cl is an unknown x.

• A. F
• B. Cl
• C. I
• D. At

Explanation: Astatine is extremely rare and is considered one of the rarest naturally occurring elements on Earth.

• A. Phosphorous
• B. Sulphur
• C. Oxygen
• D. Both A & C

Explanation: Sulphur is the correct answer as it has the largest number of allotropic forms, including rhombic, monoclinic, plastic, and…

• A. Aluminium.
• B. Potasium.
• C. Sodium.
• D. Calcium.

Explanation: In aluminum or aluminum alloy casting, the bubbles of an inert gas like argon or nitrogen are passed through the molten metal to perform…

• A. Xenon
• B. Radon
• C. Argon
• D. Krypton

Explanation: Explanation:Xenon is used in bacterial lamps, also known as excimer lamps, which are used to disinfect air and surfaces in hospitals and…

• A. Electron affinity
• B. Lattice energy
• C. Ionization energy
• D. Crystal energy

Explanation: A is incorrect as electron affinity is the amount of energy released when an electron attaches to a neutral atom or molecule in the…

• A. A gradual increase
• B. A gradual decrease
• C. First decrease then increase
• D. First increase then decrease

Explanation: A is correct because as we move further along a group, mass of the atoms increases due to increased no.

• A. HF
• B. HI
• C. HCl
• D. HBr

Explanation: A is incorrect as HF is not a strong acid.B is correct as Iodine and hydrogen have the lowest bond energy,hence less energy would be…

• A. Ne < N < C < B
• B. B < N < C < Ne
• C. B < C < N < Ne
• D. Ne < B < C < N

Explanation: As they move along the period towards the right the ionization energy increases. It is a fact and should be memorised.

• A. Electron Affinity
• B. Non-metallic character
• C. Atomic Radius
• D. Melting point upto group IV

Explanation: The atomic radius decreases as we move along the period from left to right.

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

Explanation: Silicon has a giant covalent structure and a lot of heat is required to break the strong covalent bonds hence it has the highest melting…

• A. Nitrogen requires a catalyst
• B. Oxygen is very inactive
• C. Oxygen is found in less concentration
• D. Nitrogen is highly inactive gas

Explanation: Option A is a true statement, but it does not, by itself, explain why nitrogen does not react under normal conditions; Nitrogen is highly…