All Free Chemistry MCQs with Answers

• A. Increases
• B. Becomes constant
• C. Decreases
• D. Becomes zero

Explanation: The correct answer is Option D: Becomes zero. A horizontal line on a concentration-time graph indicates that there is no change in…

• A. Molecularity of a reaction is always the same as the order of reaction
• B. In some cases, the molecularity of a reaction is the same as the order of reaction
• C. Molecularity of a reaction is always greater than the order of reaction
• D. All statements above are correct

Explanation: True for elementary reactions, where the rate law can be written directly from the stoichiometry.Example: A→productsA → productsA→products…

• A. Reactants and activated complex
• B. Reactants and the products
• C. Products and the activated complex
• D. Reactants

Explanation: The activation energy is the minimum energy required to initiate a chemical reaction, appearing as a potential energy hill between the…

• A. Decrease in activation energy of reaction
• B. Decrease in the number of collisions between molecules of reactants
• C. Increase in activation energy of molecules of reactants
• D. Increase in number of effective collisions

Explanation: As temperature increases, the kinetic energy of molecules also increases.

• A. Young needs to be encouraged and supported in society.
• B. A young need to be encouraged and supported in society.
• C. The young needs to be encouraged and supported in society.
• D. The young need to be encouraged and supported in society.

Explanation: The correct choice is D because it is grammatically correct and conveys the intended meaning.

• A. Formaldehyde
• B. Aceteldehyde
• C. Acetone
• D. Ethanol

Explanation: Formaldehyde does not have a methyl group adjacent to a carbonyl group, which is necessary for the iodoform reaction to occur.

• A. Option A: Gem diol with no electron-withdrawing groups
• B. Option B: Gem diol with a weak electron-withdrawing group
• C. Option C: Gem diol with a strong electron-withdrawing group
• D. Option D: Gem diol with a bulky substituent

Explanation: The stability of a geminal diol is significantly influenced by the presence of electron-withdrawing groups attached to the carbon that…

• A. 2, 4 - DNPH
• B. Iodine in NaOH
• C. Sodium nitroprusside
• D. hydrogen cyanide

Explanation: Iodoform test (I₂ / NaOH) is the correct reagent for distinguishing methyl ketones

• A. Pressure = high density = high
• B. Pressure = low density = high
• C. Pressure = high density = low
• D. Pressure = low density = low

Explanation: The physically correct condition is low pressure and high temperature, which corresponds to low density.

• A. Pressure = high density = high
• B. Pressure = low density = high
• C. Pressure = hight density = low
• D. Pressure = low density = low

Explanation: Real gases approximate ideal gas behavior at relatively low density, low pressure, and high temperature.At high temperatures, the gas…

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

Explanation: At low pressure P, volume V is high. V-b will approximately be equal to V so b is neglegibe.

• A. H2SO4
• B. HNO3
• C. both A and B
• D. none

Explanation: Sulfur dioxide is oxidised to sulfuric acid and nitrogen oxides form nitric acid in atmospheric moisture, so acid rain commonly contains…

• A. It helps to predict the direction of the reaction
• B. It tells about the extent of the reaction
• C. It tells about the rate of reaction
• D. None of these

Explanation: The equilibrium constant, Kc, is a measure of the ratio of product concentrations to reactant concentrations at equilibrium for a given…

• A. Al
• B. B
• C. Si
• D. C

Explanation: Borax is the sodium salt of tetraboric acid. It is the most important of all borates .Borax occurs as a natural deposit called tincal in…

• A. Acidic oxide
• B. Basic oxide
• C. Amphoteric oxide
• D. None of these

Explanation: Oxides of relatively less electropositive elements, such as BeO, Al2O3 Bi2O3 and ZnO are amphoteric and behave as acids towards strong…

• A. As antiseptic in medicine
• B. For washing eyes
• C. In soda bottles
• D. For enamels and glazes

Explanation: Uses of Boric Acid1. Boric acid is used in medicines as an antiseptic, e.g.

• A. N2O4
• B. NO
• C. NO2
• D. None of these

Explanation: As Ferrous sulphate reacts with Nitrogen oxide, a compound called Nitroso ferrous sulphate is formed which is responsible for brown ring…

• A. Their oxides are basic
• B. Their oxides and hydroxides are water soluble
• C. both a and b
• D. They are found in earth

Explanation: Alkali metals form basic oxides (e.g., Li₂O, Na₂O) which readily react with water to form strong alkaline solutions.Their hydroxides are…

• A. Small size
• B. High charge density
• C. Lower electropositivity
• D. All of the above

Explanation: Lithium's small size, high charge density, and lower electropositivity compared to its heavier alkali metal family members lead to…

• A. Francium
• B. Cesium
• C. Radium
• D. Rubidium

Explanation: RadiumHere's why:Francium, Caesium, and Rubidium are all part of Group 1 (also known as Group IA) in the periodic table, which corresponds…