All Free Chemistry MCQs with Answers

• A. Has fixed value at fixed temperature
• B. Changes with change in temperature
• C. Does not depend upon concentration of reactants
• D. None of the above

Explanation: The explanation for this question will be added soon.

• A. Unit rate constant
• B. Specific rate constant
• C. Relative rate constant
• D. Average rate constant

Explanation: A specific rate constant at a given temperature may be defined as the rate of reaction when the molar concentration of each reactant is…

• A. It is independent of concentration of reactants.
• B. It depends upon the temperature.
• C. It does not depend upon the order of reaction.
• D. All of the above options are correct.

Explanation: Option a) "It is independent of the concentration of reactants" is not true about the rate of reaction.

• A. Reaction time
• B. Reaction Speed
• C. Rate of reaction
• D. All of these options are correct

Explanation: A. Reaction time (Incorrect): Reaction time refers to the time it takes for a reaction to occur, not the rate of the reaction represented…

• A. No units
• B. Unit of moles/dm3
• C. Unit of moles/litre
• D. Unit of moles/dm3s-1

Explanation: The formula for the rate of reaction is concentration/time. Unit for concentration is mol/dm3 and the unit for time is s.

• A. Mole/ litre
• B. Moles/ gram
• C. Moles/ Second
• D. moles/dm3 s-1

Explanation: Reaction rates are usually expressed as the concentration of reactant consumed or the concentration of product formed per unit time.

• A. Reaction time
• B. Reaction Speed
• C. Rate of reaction
• D. All of these

Explanation: Correct option is C. The reaction rate or rate of reaction is the speed at which a chemical reaction takes place, defined as proportional…

• A. Temperature
• B. Pressure
• C. Time
• D. None of these options are correct

Explanation: dx/dt is the rate of change of concentration with respect to time. It is a mathematical expression that represents the change in the…

• A. At equilibrium
• B. One instant
• C. Given temperature
• D. Given pressure

Explanation: As the name indicates, the instantaneous rate of a reaction is the rate of the reaction at any instant. So option B is the correct option.

• A. Rate of reaction
• B. Pressure
• C. Conditions
• D. Both A and C

Explanation: Chemical equations tell about the pressure through the number of moles but not the "rate of reaction" and the "conditions of the reaction"…

• A. Rising
• B. Falling
• C. U shaped
• D. None of these

Explanation: The concentration of reactant decreases with respect to time so the curve in the concentration-time graph should be "falling".

• A. Rubidium
• B. Potassium
• C. Sodium
• D. Cesium

Explanation: Options A, B and D are incorrect as Na is the uppermost element in alkali metals and down the group, electropositive character or metallic…

• A. NH4+
• B. K+
• C. Mg2+
• D. Al3+

Explanation: b) K+ (potassium ion):The potassium ion (K+) produces a characteristic lilac or violet flame color during a flame test.

• A. Element sodium can be prepared and isolated by electrolyzing an aqueous solution of NaCl
• B. Elemental Na is a strong oxidizing agent
• C. Elemental Na is insoluble in NH3
• D. Elemental Na is easily oxidizing

Explanation: Good reducing agents include the active metals, such as sodium, magnesium, aluminum, and zinc, which have relatively small ionization…

• A. Low electronegativity
• B. Low melting point
• C. Their ions are isoelectronic with noble gas
• D. High ionization energy

Explanation: Alkali metals have low ionization energies due to their larger atomic radii.

• A. Electron affinity
• B. Reactivity
• C. Ionisation energy
• D. All of the above options are correct

Explanation: The reactivity of Group I elements increases as you go down the group because: the atoms get larger as you go down the group.

• A. Ionization energy
• B. Reactivity
• C. Electron affinity
• D. Electronegativity

Explanation: The reactivity of alkali metals increases as you go down the group because: the atoms get larger as you go down the group.

• A. NaCl
• B. NaOH
• C. NaBr
• D. ClO

Explanation: Option A: When molten sodium (Na) comes into contact with chlorine (Cl₂) gas, a vigorous reaction takes place, resulting in the formation…

• A. Their oxides are basic
• B. Their oxides and hydroxides are water-soluble and form alkaline solutions in water
• C. Both a & b
• D. They are found in the earth

Explanation: Option A: Their oxides are basic: This option refers to the fact that alkali metals form oxides that have basic properties.

• A. Nelson's Cell
• B. Hg- Cell
• C. Castner Kellner Cell
• D. All of these

Explanation: Option A: Nelson's Cell, also called the Mercury Cell or Castner-Kellner Cell, is one type of electrolytic cell used for the production of…