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

Answer: (c) Al
Explanation:
Just as Li shows resemblance with its diagonally opposite element Al. This is because the two elements have the same electronegativity (Be = 1.5, Al = 1.5) and possess similar polarizing power (i.e., charge/radius).

Answer: (a) Na
Explanation:
When carbonates are heated they decompose to form the oxide. Sodium carbonate and potassium carbonate do not decompose. The carbonates become more difficult to decompose as we go down the group.

Answer: (c) Ca(OCl)₂
Explanation:
Calcium hypochlorite is a compound with formula Ca (ClO)₂. As a mixture with lime and calcium chloride, it is marketed as chlorine powder or bleach powder for water treatment and as a bleaching agent.
Calcium hypochlorite is produced industrially by treating lime (Ca(OH)₂) with chlorine gas.
2Cl₂ + 2Ca(OH)₂ → Ca(OCl)₂ + CaCl₂ + 2H₂O

Answer: (d) Castner – Kellner cell.
Explanation:
In the Castner-Kellner method, electrolysis of brine solution is performed in order to obtain sodium hydroxide.

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: (c) Calcium Oxalate
Explanation:
Calcium oxalate is the main component of kidney stone.

Answer: (d) Li
Explanation:
All group 1 compounds (metal nitrates) decompose to give metal nitrates and
oxygen → 2MNO₃ ​→ 2MNO₂ + O₂
​Since Lithium shows diagonal relationship with magnesium, it shows different behaviour
4LiNO₃​ → 2Li₂​O + 4NO₂ ​+ O₂
​(Its nitrate decomposes like Group 2 elements)

Answer: (a) LiCO₃ & MgCO₃
Explanation:
Lithium carbonate and magnesium carbonate are thermally unstable. They decompose on heating. Properties of Li are similar to Mg because of diagonal relationship.
Li₂CO₃ → Li₂O + CO₂
MgCO₃ → MgO + CO₂
Li₂​CO₃ and MgCO₃ are salts of weak acid (CO₂) with weak bases LiOH and Mg(OH)₂. On the other hand, NaOH and KOH are much stronger bases and can hold the CO₂ easily. Thus, sodium carbonate and potassium carbonate are thermally stable. They do not decompose on heating.

Answer: (b) Mg,Ca
Explanation:
Relative to other group 2 elements, Be and Mg atoms are smaller in size. Thus, the electrons in Be and Mg are too strongly bound to get excited by flame. In other words, the energy required to excite electrons in Be and Mg atoms does not lie in the visible range.

Answer: (b) K
Explanation:
Actually Rb emits the longest wavelength light in flame test. Since Rb is one there in the options, therefore, correct option should be K

Answer: (d) 124 gm

Answer: (c) Hydration energy of cations
Explanation:
The stability of the carbonates of the alkaline earth metals increases on moving down the group. The solubility of carbonate of metals in water is generally low. However, they dissolve in water containing CO₂ yielding bicarbonates, and this solubility decreases on going down in a group with the increase in stability of carbonates of metals, and decrease in hydration energy of the cations.

Answer: (c) Li₂O, CO₂
Explanation:
Lithium carbonate is unstable carbonate due to polarizing power of Li⁺. Hence it undergoes easy dissociation just like alkaline earth metal carbonates upon heating to give lithium oxide and carbon dioxide.
Li₂CO₃ → Li₂O + CO₂

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: (b) Beryllium
Explanation:
Beryllium does not exhibit coordination number more than four as in its valence shell there are only four orbitals. The remaining members of the group can have a coordination number of six by making use of d-orbitals.

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

Answer: (c) Caesium
Explanation:
Among the given metals, Cesium(Cs) has lowest ionization enthalpy. Hence it loses electrons readily. Therefore, cesium is used in solar cells.

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

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: (c) Both (1) and (2) are true
Explanation:
Mono valent sodium and potassium ions and divalent magnesium and calcium ions are found in large proportions in biological fluids. These ions perform important biological functions such as maintenance of ion balance and nerve impulse conduction.