All Free Chemistry MCQs with Answers

• A. Ne and Ar
• B. He and Ne
• C. Ar and He
• D. Any of the noble gas can be used

Explanation: Glass lasers are formed from a combination of argon (Ar) and helium (He) gases.

• A. Mn
• B. Ni
• C. Cu
• D. Zn

Explanation: Zinc (Zn) has the minimum melting and boiling point among the given options.

• A. It is also called diaphragm cell
• B. Used for commercial preparation of NaOH
• C. The level of brine in the cathodic compartment is higher than anodic compartment
• D. Constant level device is used

Explanation: Nelson Cell, also known as the diaphragm cell, is an electrolytic cell used for the commercial preparation of sodium hydroxide (NaOH) and…

• A. H2S
• B. H2SO4
• C. H2O
• D. KMnO4

Explanation: Potassium permanganate (KMnO4) is both an oxidizing and reducing agent, depending on the conditions of the reaction.

• A. Filtration
• B. Common ion effect
• C. Crystallization
• D. Chromatography

Explanation: Crystallization is a technique based on the different solubilities of the components in a solution.

• A. to increase ionization of NH4OH due to common ion effect
• B. to decrease ionization of NH4OH due to common ion effect
• C. to increase the solubility of NH4OH in water
• D. to thicken the precipitates of hydroxides of Al3+ and Fe3+

Explanation: NH4Cl, when dissolved in water, dissociates into NH4+ and Cl- ions. When NH4Cl is added before NH4OH in the analysis of Group III cations…

• A. More ions can be produced due to presence of two half cells
• B. Chemical reaction between the solutions of two half cells does not take place
• C. More current can be generated due to two half cells
• D. None of the above

Explanation: In a galvanic cell, two half cells are employed to facilitate the redox reaction by separating the oxidation and reduction reactions…

• A. Normal elements
• B. Less typical elements
• C. Block "p" elements
• D. Block "f" elements

Explanation: Sub-group "B" of the periodic table refers to the transition metals, which are characterized by their partially filled d orbitals.

• A. Electron affinity
• B. Energy release
• C. Energy absorption
• D. Both options A and C are correct

Explanation: When an electron is added to an atom, the energy change associated with this process is known as the electron affinity.

• A. Electron affinity
• B. Energy release
• C. Energy absorption
• D. Both options A and C are correct

Explanation: Electron affinity is defined as the energy change that occurs when a gaseous atom gains one electron to form a negatively charged ion.

• A. For chlorophyll development
• B. As fertilizer
• C. For neutralizing acidic soils
• D. To increase fruit production

Explanation: One of the important uses of lime in agriculture is for neutralizing acidic soils.

• A. 4
• B. 3
• C. 2
• D. 1

Explanation: In the typical tetrahedral structure of quartz crystal, each oxygen atom is connected to 4 silicon atoms.

• A. II-A
• B. III-A
• C. I-A
• D. IV-B

Explanation: Li is an element of group I-A. This is because it has one valence electron, which it readily loses to form a +1 cation.

• A. Down's cell
• B. Castner-kellner process
• C. Dutch's method
• D. Nelson's process

Explanation: Sodium is primarily prepared by the Down's cell. This method involves the electrolysis of molten sodium chloride (NaCl) to produce sodium…

• A. Li₂CO₃
• B. MgCO₃
• C. Both a and b
• D. Both are stable

Explanation: Li₂CO₃ is unstable and decomposes on heating to form Li₂O and CO₂. This is because lithium is a small, highly electropositive element, and…

• A. Higher
• B. Lower
• C. Same
• D. Varies

Explanation: The melting point of Group I-A elements is lower than Group II-A elements.

• A. Li
• B. Mg
• C. Both
• D. None of these

Explanation: Both Li and Mg are highly reactive metals and do not occur in their free state in nature. They are found in combined states as compounds.

• A. Carbon
• B. Sulphur
• C. Nitrogen
• D. Calcium
• E. Both b and d

Explanation: Gypsum (CaSO₄·2H₂O) is a naturally occurring mineral that supplies both sulfur and calcium to the soil.

• A. It causes painful burns
• B. It has purgative smell
• C. It is manufactured by Castner-Kellner process
• D. It is used as an anti-acid
• E. Both b and d

Explanation: Caustic soda (NaOH) is a strong base. It causes painful burns on contact with skin. It is manufactured by the Castner-Kellner process.

• A. MgSO₄.H₂O
• B. MgSO₄.7H₂O
• C. CaSO₄.2H₂O
• D. PbCr₂O₇

Explanation: Epsom salt is a hydrated magnesium sulfate with the formula MgSO₄.7H₂O.