S-block elements practice · Mixed difficulty

Option A (If both Statement-I and Statement-II are true, and Statement-II is the correct explanation of Statement-I) is correct because the hydrogen carbonates of alkali metals are soluble but less soluble than normal carbonates due to hydrogen bonding.

Option B ($\mathrm{Mg}$) is correct because magnesium forms polymeric hydrides, not ionic hydrides.

Option A is correct because alkali metals form ionic hydrides with H-, and their low electronegativity and conductive properties when fused support this.

Option D ($\mathrm{MgCl}_2$) is correct because magnesium and beryllium have high ionization energies due to their small size, preventing them from being easily excited in a flame.

Option A (${BeSO}_4$) is correct because beryllium sulfate is readily soluble in water due to the small size and high charge density of the beryllium ion, leading to high hydration energy.

Option B (Presence of trace of $Na{O_2}$) is correct because the light yellow color of $N{a_2}{O_2}$ is due to the presence of $Na{O_2}$ as an impurity.

Option D ($N{a_2}C{O_3}.10{H_2}O$) is correct because washing soda is sodium carbonate decahydrate, $N{a_2}C{O_3}.10{H_2}O$.

The correct answer is C (Carbinol) because carbinol (methanol) is an alcohol and does not have sufficient acidity to react with $\mathrm{NaHCO}_3$ to release $CO_2$.

Option D ($K,\,\,Cs$) is correct because Potassium (K) and Cesium (Cs) have relatively low ionization energies and are commonly used in photoelectric cells.

Option C ($Be(OH)_2$) is correct because beryllium hydroxide ($Be(OH)_2$) is amphoteric and practically insoluble in water, unlike the other alkaline earth metal hydroxides which have increasing solubility down the group.

Option D ($\mathrm{MgS}{\mathrm{O}_4}$) is correct because $Na_2CO_3$ reacts with $MgSO_4$ to form a precipitate of magnesium carbonate, while $NaHCO_3$ does not.

Option B (Beryllium chloride) is correct because beryllium chloride (BeCl₂) is covalent due to the small size and high polarizing power of Be²⁺, making it soluble in organic solvents.

Option B ($\mathrm{CaSO}_4 \cdot 2 \mathrm{H}_2 \mathrm{O}$) is correct because Gypsum ($\mathrm{CaSO}_4 \cdot 2 \mathrm{H}_2 \mathrm{O}$) is added to Portland cement to control the setting time.

Option B (Magnesium oxide) is correct because electric cookers are coated with magnesium oxide to protect them against fire.

Option B ($K{O_2}$) is correct because potassium, when heated strongly in oxygen, forms potassium superoxide ($K{O_2}$).

Option C ($\mathrm{CaC}{\mathrm{O}_3}$) is the correct answer because sedimentary rocks laid down under water mainly contain calcium carbonate.

The correct answer is A ($Na_2O_2+HCl$) because a mixture of sodium peroxide and hydrochloric acid is commercially known as oxone and is used as a bleaching agent.

Option D ($\mathrm{N}{\mathrm{a}_2}\mathrm{C}{\mathrm{O}_3} \cdot 10{\mathrm{H}_2}\mathrm{O}$) is correct because washing soda is sodium carbonate decahydrate.

Option A ($\mathrm{LiHCO_3}$) is correct because lithium bicarbonate ($\mathrm{LiHCO_3}$) is unstable in solid form and exists only in solution.

Option A (Calcium chloride) is correct because calcium chloride is a hygroscopic substance commonly used as a desiccant in laboratories.

Option C ($Ba{\left( {N{O_3}} \right)_2}$) is correct because Barium nitrate does not crystallize with water molecules.

Option B ($\mathrm{Mg}$) is correct because magnesium is the metal present in Grignard reagents, which have the general formula R-Mg-X.

Option D is correct because both MgO and SO2 are formed when Mg reacts with O2. The products depend on the amount of oxygen available and the reaction conditions.

Option A (${\mathrm{I}_2}$ solution) is correct because a standard iodine solution is commonly used to standardize sodium thiosulfate solutions in iodometric titrations.

Option B ($\mathrm{CaSO}_4 \cdot \frac{1}{2} \mathrm{H}_2 \mathrm{O}$) is correct because plaster of Paris is the hemihydrate form of calcium sulfate.

Option D (NaN{O_2},NaBr) is correct because NaN{O_2} with dilute HCl and NaBr with conc. H{_2}S{O_4} both produce reddish-brown vapors (NO{_2} and Br{_2} respectively).

Option A ($MgC{l_2}$) is correct because magnesium ions ($Mg^{2+}$) do not impart any characteristic color to the flame during a flame test due to their high ionization energy.

Option D (Water vapour is released) is correct because when washing soda is heated, it loses its water of crystallization.

Option A (Absorbs $\mathrm{C}{\mathrm{O}_2}$ and increases ${\mathrm{O}_2}$ concentration) is correct because $\mathrm{K}{\mathrm{O}_2}$ reacts with carbon dioxide to produce oxygen.

Option C ($\mathbf{A}$ is true but $\mathbf{R}$ is false) is correct because while ${FrClO}_4$ and ${Fr}_2 {PtCl}_6$ are indeed salts of low solubility, the reason that all alkali metal ions form insoluble salts is false.