MCQ Questions for Class 11 Chemistry Chapter 10 The s-Block Elements with Answers

Answer: (a) Strongly basic
Explanation:
Caesium hydroxide or cesium hydroxide (CsOH) is a chemical compound consisting of caesium ions and hydroxide ions. It is a strong base (p_kb = -1.76), much like the other alkali metal hydroxides such as sodium hydroxide and potassium hydroxide.

Answer: (b) (Na₂CO₃. 10H₂O)
Explanation:
The Solvay process or ammonia soda process is used for the manufacture of sodium carbonate
(Na₂CO₃. 10H₂O).

Answer: (a) Deep blue solution
Explanation:
When an alkali metal is dissolved in liquid ammonia, it results in the formation of a deep blue coloured solution. The ammoniated electrons absorb energy corresponding to a red region of visible light. Therefore, the transmitted light is blue in colour.

Answer: (a) Acid containing Oxygen
Explanation:
An oxyacid, oxoacid, or ternary acid is an acid that contains oxygen. Specifically, it is a compound that contains hydrogen, oxygen, and at least one other element, with at least one hydrogen atom bond to oxygen that can dissociate to produce the H⁺ cation and the anion of the acid. e.g., carbonic acid, H₂CO₃ (OC(OH)₂; sulphuric acid, H₂SO₄ (O₂S(OH)₂).

Answer: (c) Developing interlocking needle like crystals of hydrated silicates
Explanation:
Water develops interlocking needle ­like crystals of hydrated silicates. The reactions involved are the hydration of calcium aluminates and calcium silicates which change into their colloidal gels.

At the same time, some calcium hydroxide and aluminium hydroxides are formed as precipitates due to hydrolysis. Calcium hydroxide binds the particles of calcium silicate together while aluminium hydroxide fills the interstices rendering the mass impervious

Answer: (c) Calcined gypsum
Explanation:
The composition of gypsum is CaSO₄ ∙2H₂O. It does not have CaCO₃

Answer: (c) Mg
Explanation:
Carnallite is an evaporite mineral a hydrated potassium magnesium chloride. It is variably coloured yellow to white, reddish or blue. It occurs with a sequence of potassium and magnesium evaporite. It is an uncommon double chloride mineral that forms under specific conditions. It is an important source of potash.

Answer: (a) Mg
Explanation:
Magnesium metal is used for the preparation of the wire of flash bulb.

Answer: (d) KOH.
Explanation:
The basic strength increases down the group and decreases along a period.

Answer: (b) MgCl₂ × 5MgO × (xH₂O)
Explanation:
Mixture of MgCl₂ and MgO is called Sorels cement. It is MgCl₂ × 5MgO × (xH₂O)

Answer: (d) Cs.
Explanation:
Atomic size increases as we move down the alkali group. As a result, the binding energies of their atoms in the crystal lattice decrease. Also, the strength of metallic bonds decreases on moving down a group in the periodic table. This causes a decrease in the melting point. Among the given metals, Cs is the largest and has the least melting point.

Answer: (d) KOH.
Explanation:
The basic strength increases down the group and decreases along a period.

Answer: (b) Na⁺
Explanation:
Hydration energy depends on charge of ion and ionic radius. Higher the charge, greater the hydration energy. On the other hand, smaller the size, greater the hydration energy. Charge is considered first for comparison. Hence, Mg²⁺ has higher hydration energy than Na⁺.

Answer: (a) Ca(OCI)₂
Explanation:
Milk of lime reacts with chlorine to form bleaching powder.
2Ca(OH)₂ + 2Cl₂ → CaCl₂ + Ca(OCl)₂ + 2H₂O

Answer: (d) Both (2) and (3) are correct
Explanation:
Calcium carbonate is strongly heated until it undergoes thermal decomposition to form calcium oxide and carbon dioxide. The calcium oxide (unslaked lime) is dissolved in water to form calcium hydroxide (limewater).
CaCO₃ → CaO + CO₂

Answer: (c) Ca₃(PO₄)₂
Explanation:
Ca₃(PO₄)₂. Both Ca and P are needed by human beings. Also they prevent moisture absorbing power of other components such as MgCl₂, CaCl₂, CaSO₄ and MgSO₄ present in commercial sodium chloride.

Answer: (a) Strongly basic
Explanation:
Caesium hydroxide or cesium hydroxide (CsOH) is a chemical compound consisting of caesium ions and hydroxide ions. It is a strong base (p_kb = -1.76), much like the other alkali metal hydroxides such as sodium hydroxide and potassium hydroxide.

Answer: (d) Fe
Explanation:
Method of extraction of a metal depends on the reactivity of the metal. Iron (Fe) is not manufacture by electrolysis. Moderately reactive metals like zinc and iron are extracted by reduction of their oxides using carbon.

Answer: (a) Mg
Explanation:
Magnesium metal is used for the preparation of the wire of flash bulb.

Answer: (d) eutectic mixtue of CaCl/H₂O freezes at -55°C while that of NaCl/H₂O freezes at -18°C
Explanation:
Eutectic mixture of CaCl₂/H₂O freezes at -55°C while that of NaCl/H₂O freezes at -18°C.

When added to ice. NaCl and CaCl₂ ionise into respective ions (Na⁺, Ca²⁺ & Cl^–) this leads to increase in the number of particles (ions). As CaCl₂ has greater number of ions, Increasing the number of particles /ions increases the vant hoff factor. Vant hoff factor is directly proportional to the depression in freezing point thus lowers the freezing point of ice causing preventing the formation of ice.