All Free Chemistry MCQs with Answers

• A. CaCl2
• B. CaSO4
• C. HClO
• D. Ca(ClO3)2

Explanation: The correct answer is HClO. The bleaching action of bleaching powder is due to the formation of hypochlorous acid (HClO).

• A. d-d transition in the solvated metal ion
• B. presence of unpaired electron
• C. charge - transfer transition
• D. absorption of light by the solvated electrons.

Explanation: Alkaline earth metals produce a bright blue color when dissolved in liquid ammonia due to the presence of solvated electrons.

• A. Mg(NO3)2
• B. Mg3N2
• C. NH3
• D. MgO

Explanation: The correct answer is Mg3N2. When magnesium (X) is heated in nitrogen, it forms magnesium nitride (Y).

• A. Ba(OH)2
• B. Mg(OH)2
• C. Sr(OH)2
• D. Ca(OH)2

Explanation: Barium hydroxide (Ba(OH)2) is the correct answer. The solubility trend of hydroxides of Group 2A metals increases as you move down the…

• A. KO2
• B. SiO2
• C. TiO2
• D. BaO2

Explanation: KO2 (potassium superoxide) is the correct answer as it contains an unpaired electron, making it paramagnetic and attracted to a magnetic…

• A. Al3+
• B. Na+
• C. Be2+
• D. Mg3+

Explanation: The correct answer is option B: Na^+. The hydration energy of Mg^2+ is greater than that of Na^+ because Na^+ has lesser ionization energy…

• A. Al4C3
• B. CaC2
• C. VC2
• D. SiC2

Explanation: Aluminum carbide (Al4C3) is the correct answer as it reacts with water to produce aluminum hydroxide and methane.

• A. NO
• B. N2O
• C. H2
• D. NO2

Explanation: When magnesium reacts with very dilute nitric acid, it forms magnesium nitrate and hydrogen gas is evolved.

• A. NaOH, Na2O, Li2O
• B. Na2CO3, Na2O2, Li2O
• C. Na2O, Li3N, NH3
• D. Na2O, Li2O, Li3N

Explanation: When Na and Li are placed in dry air, we get a mixture of sodium oxide (Na2O) and lithium oxide (Li2O).

• A. H-(aq) + H2O → H3O+
• B. H-(aq) + H2O → OH- + H2
• C. H- + H2O→ H2 + O2
• D. H- + H2O → No reaction

Explanation: When sodium hydride (NaH) is dissolved in water, the hydride ion (H-) being a stronger base than hydroxide ion (OH-) reacts with water to…

• A. X is lithium hydride (LiH)
• B. X is BeH2
• C. X is beryllium dichloride dihydrate (BeCl2 · 2H2O)
• D. X is beryllium hydride (BeH2)

Explanation: In the given chemical equation, BeCl2 reacts with LiAlH4 to produce 2BeH2, LiCl, and AlCl3. Therefore, the correct identity of X is BeH2.

• A. NaAlO2
• B. NaHCO3
• C. Na2CO3
• D. Na2O2

Explanation: During the reaction, Na reacts with Al2O3 at high temperatures to yield Na2O and Al.

• A. Cs-Br covalent bonds
• B. Cs3+ and Br- ions
• C. Cs+ and Br3- ions
• D. Cs3+ and Br33- ion

Explanation: CsBr3 is an ionic compound. Cs is a monovalent ion, i.e., Cs+. So, the other ion will be Br3−.

• A. NaNO3
• B. KNO3
• C. Na2CO3
• D. LiNO3

Explanation: Upon heating, LiNO3 decomposes as follows: 4LiNO3 → 2Li2O + 4NO2 + O2. The decomposition releases nitrogen dioxide (NO2), a coloured gas…

• A. Only CO2 is released
• B. CO & CO2 are released
• C. Only CO is released
• D. Water vapour is released

Explanation: When washing soda is heated, it loses all water of crystallisation and becomes anhydrous sodium carbonate.

• A. Exhibiting amphoteric nature of oxides
• B. Forming polymeric hydrides
• C. Forming covalent halides
• D. Exhibiting maximum covalence in compounds

Explanation: The correct answer is that Be and Al differ in exhibiting the maximum covalency in compounds.

• A. Na2CO3
• B. K2CO3
• C. Ca(HCO3)2
• D. CaCO3

Explanation: Upon heating, compound 'X' decomposes into CaO and CO2. The residue from this reaction, when mixed with water, forms Ca(OH)2 (Y).

• A. It can form nitride when heated in air.
• B. It reacts with water to form hydroxide and hydrogen.
• C. It is soluble in liquid ammonia.
• D. Its nitrate is thermally unstable.

Explanation: Lithium stands out from other alkali metals as it is the only one capable of forming nitride when heated in air.

• A. Ba2+
• B. K+
• C. Li+
• D. Be2+

Explanation: Be2+ has the largest heat of hydration due to its small size and high charge, leading to high polarising power and attraction of multiple…

• A. Two moles of ammonia
• B. One mole of nitric acid
• C. One mole of ammonia
• D. Two moles of nitric acid

Explanation: When one mole of magnesium nitride reacts with an excess of water, it produces two moles of ammonia according to the balanced chemical…