All Free Chemistry MCQs with Answers

• A. CO₂
• B. NO
• C. N₂
• D. CO

Explanation: The correct answer is Option D: CO. Carbon monoxide (CO) is a flammable gas that, when burned in oxygen, produces a blue flame due to its…

• A. 4
• B. 2
• C. 1
• D. 6

Explanation: In the network structure of silica (SiO₂), each silicon atom is covalently bonded to four oxygen atoms in a tetrahedral arrangement…

• A. Li and Be
• B. Mg and Ca
• C. Na and K
• D. C and Si

Explanation: The correct answer is Option D: C and Si. Both carbon and silicon are non-metals that form acidic oxides.

• A. Trigonal
• B. Cubic
• C. Linear
• D. Tetrahedral

Explanation: The correct geometry around each Si-atom in SiO₂ is tetrahedral. This is because silicon typically forms four covalent bonds, and in SiO₂…

• A. SiO₄⁴⁻
• B. SiO₃²⁻
• C. SiO₂
• D. SiO₄

Explanation: The correct answer isSiO₂because quartz, opal, and sand predominantly consist of silicon dioxide, which has the empirical formula SiO₂.

• A. -R
• B. -OH
• C. HCO3⁻
• D. O₂

Explanation: Silicones are polymeric compounds in which silicon atoms are bonded to organic groups, typically alkyl or aryl groups, denoted as -R.

• A. SiO₂ + H₂
• B. Si(OH)₄ + H₂
• C. SiO₂ + SiH₄
• D. SiH₄ + O₂

Explanation: When silicon is exposed to steam at red-hot temperatures, it forms silicon dioxide (SiO₂) and releases hydrogen gas (H₂) as a byproduct.

• A. Si(OH)₄
• B. Al(OH)₃
• C. Mg(OH)₂
• D. Ca(OH)₂

Explanation: The correct answer is Si(OH)₄. Silicon hydroxide behaves as an acid due to its structure that allows it to release protons.

• A. Carbon
• B. Silicon
• C. Tin
• D. Lead

Explanation: The correct answer is Carbon. Carbon tetrachloride (CCl4) is known for its lack of reactivity with water because it is non-polar and lacks…

• A. PbCl₄
• B. CCl₄
• C. SiCl₄
• D. GeCl₄

Explanation: Among the options provided, SiCl₄ reacts most violently with cold water.

• A. Carbon is non-metal while silicon is semi-metal
• B. CO₂ is an independent molecule while SiO₂ has a network covalent structure
• C. Carbon forms acidic oxide but silicon forms basic oxide
• D. CO₂ and SiO₂ have the same hybridization

Explanation: The correct answer is Option B. CO₂ is a linear molecule composed of discrete units, which are held together by weak van der Waals forces…

• A. BeO
• B. Al₂O₃
• C. CO₂
• D. CaO

Explanation: The correct answer is CO₂. It is an acidic oxide that generates carbonic acid (H₂CO₃) upon interaction with water.

• A. Silicates
• B. Individual form
• C. Both silicates and individual form
• D. None

Explanation: Alkali metals, due to their high reactivity, are rarely found in their pure elemental form.

• A. I only
• B. II only
• C. III and IV only
• D. I, II, III and IV

Explanation: All of the statements are correct. The atomic and ionic radii increase from Li to Cs with the increasing atomic number due to the addition…

• A. They are known as alkaline earth metals
• B. They have two electrons in the outermost shell and occupy s sub-shell
• C. Their atomic radii increase down the group
• D. Ionization energy of Ca is higher than that of Mg

Explanation: The incorrect statement about the alkaline earth metals is that the ionization energy of calcium (Ca) is higher than that of magnesium…

• A. NH3
• B. N2H4
• C. N2H2
• D. N3H

Explanation: N3H (hydrazoic acid) is the acidic hydride of nitrogen. Hydrazoic acid, chemical formula N3H, is an acidic hydride of nitrogen.

• A. Increases
• B. Decreases
• C. Constant
• D. None

Explanation: In metals, as the atomic size increases, the boiling point generally decreases.

• A. Na+
• B. Mg2+
• C. Al3+

Explanation: Hydration energy is the energy released when ions are surrounded by water molecules.

• A. Diamond
• B. Graphite
• C. Phosphorus
• D. B and C

Explanation: Graphite is the only conductor in the given options. The structure of graphite allows electrons to move freely within its layers, making…

• A. Oxidation of lead to lead oxide
• B. Oxidation of lead to red lead
• C. Dissolution of lead in water containing air
• D. Making lead wires by forcing heated metal through a die

Explanation: Option C is correct. Plumbo-solvency refers to the dissolution of lead in water containing air.