CBSE Class 11 Chemistry VBQs S Block Elements

Question. Ionic mobility of which of the following alkali metal ions is lowest when aqueous solution of their salts are put under an electric field?
(a) K
(b) Rb
(c) Li
(d) Na 
Answer. C

Question. Which one of the alkali metals, forms only, the normal oxide, M₂O on heating in air?
(a) Rb
(b) K
(c) Li
(d) Na 
Answer. C

Question. The ease of adsorption of the hydrated alkali metal ions on an ion-exchange resins follows the order
(a) Li⁺ < K⁺ < Na⁺ < Rb⁺
(b) Rb⁺ < K⁺ < Na⁺ < Li⁺
(c) K⁺ < Na+ < Rb+ < Li⁺
(d) Na⁺ < Li+ < K⁺ < Rb⁺
Answer. B

Question. The sequence of ionic mobility in aqueous solution is
(a) Rb+ > K⁺ > Cs+ > Na⁺
(b) Na⁺ > K⁺ > Rb⁺ > Cs⁺
(c) K⁺ > Na⁺ > Rb⁺ > Cs⁺
(d) Cs⁺ > Rb⁺ > K+ > Na⁺
Answer. D

Question. When a substance (A) reacts with water it produces a combustible gas (B) and a solution of substance (C) in water. When another substance (D) reacts with this solution of (C), it also produces the same gas (B) on warming but (D) can produce gas (B) on reaction with dilute sulphuric acid at room temperature.Substance (A) imparts a deep golden yellow colour to a smokeless flame of Bunsen burner. Then (A),
(B), (C) and (D) respectively are
(a) Ca, H₂, Ca(OH)₂, Sn
(b) K, H₂, KOH, Al
(c) Na, H₂, NaOH, Zn
(d) CaC₂, C₂H₂, Ca(OH)₂, Fe 
Answer. C

Question. Which one of the following properties of alkali metals increases in magnitude as the atomic number rises?
(a) Ionic radius
(b) Melting point
(c) Electronegativity
(d) First ionization energy 
Answer. A

Question. In the case of alkali metals, the covalent character decreases in the order
(a) MF > MCl > MBr > MI
(b) MF > MCl > MI > MBr
(c) MI > MBr > MCl > MF
(d) MCl > MI > MBr > MF
Answer. C

Question. The alkali metals form salt-like hydrides by the direct synthesis at elevated temperature. The thermal stability of these hydrides decreases in which of the following orders?
(a) NaH > LiH > KH > RbH > CsH
(b) LiH > NaH > KH > RbH > CsH
(c) CsH > RbH > KH > NaH > LiH
(d) KH > NaH > LiH > CsH > RbH 
Answer. B

Question. Which compound will show the highest lattice energy?
(a) RbF
(b) CsF
(c) NaF
(d) KF 
Answer. C

Question. Which of the alkali metal chloride (MCl) forms its dihyrate salt (MCl.2H₂O) easily ?
(a) LiCl
(b) CsCl
(c) RbCl
(d) KCl
Answer. A

Question. Crude sodium chloride obtained by crystallisation of brine solution does not contain
 (a) MgSO₄
(b) Na₂SO₄
(c) MgCl₂
(d) CaSO₄
Answer. A

Question. In Castner-Kellner cell for production of sodium hydroxide
(a) brine is electrolyzed using graphite electrodes
(b) molten sodium chloride is electrolysed
(c) sodium amalgam is formed at mercury cathode
(d) brine is electrolyzed with Pt electrodes.
Answer. C

Question. Which of the following statements is incorrect?
(a) Pure sodium metal dissolves in liquid ammonia to give blue solution.
(b) NaOH reacts with glass to give sodium silicate.
(c) Aluminium reacts with excess NaOH to give Al(OH)₃.
(d) NaHCO₃ on heating gives Na₂CO₃.
Answer. C

Question. In which of the following processes, fused sodium hydroxide is electrolysed at a 330 °C temperature for extraction of sodium?
(a) Castner’s process
(b) Down’s process
(c) Cyanide process
(d) Both (b) and (c).
Answer. A

Question. Which of the following is known as fusion mixture?
(a) Mixture of Na₂CO₃ + NaHCO₃
(b) Na₂CO₃.10H₂O
(c) Mixture of K₂CO₃ + Na₂CO₃
(d) NaHCO₃
Answer. C

Question. Washing soda has formula
(a) Na₂CO₃.7H₂O
(b) Na₂CO₃.10H₂O
(c) Na₂CO₃.3H₂O
(d) Na₂CO₃
Answer. B

Question.The following metal ion activates many enzymes,participates in the oxidation of glucose to produce ATP and with Na, is responsible for the transmission of nerve signals.
(a) Iron
(b) Copper
(c) Calcium
(d) Potassium
Answer. D

Question. The function of “Sodium pump” is a biological process operating in each and every cell of all animals. Which of the following biologically important ions is also a constituent of this pump?
(a) K⁺
(b) Fe²⁺
(c) Ca²⁺
(d) Mg²⁺ 
Answer. A

Question. Magnesium reacts with an element (X) to form an ionic compound. If the ground state electronic configuration of (X) is 1s² 2s² 2p³, the simplest formula for this compound is
(a) Mg₂X₃
(b) MgX₂
(c) Mg₂X
(d) Mg₃X₂ 
Answer. D

Question. Electronic configuration of calcium atom may be written as
(a) [Ne] 4p²
(b) [Ar] 4s²
(c) [Ne] 4s²
(d) [Ar] 4p²
Answer. B

Question. Compared with the alkaline earth metals, the alkali metals exhibit
(a) smaller ionic radii
(b) highest boiling points
(c) greater hardness
(d) lower ionization energies. 
Answer. D

Question. Which of the following atoms will have the smallest size?
(a) Mg
(b) Na
(c) Be
(d) Li 
Answer. C

Question. HCl was passed through a solution of CaCl₂, MgCl₂, and NaCl. Which of the following compound(s) crystallise(s)?
(a) Both MgCl₂ and CaCl₂
(b) Only NaCl
(c) Only MgCl₂
(d) NaCl, MgCl₂ and CaCl₂
Answer. B

Question. Which of the following is an amphoteric hydroxide?
(a) Be(OH)₂
(b) Sr(OH)₂
(c) Ca(OH)₂
(d) Mg(OH)₂
Answer. A

Question. Among CaH₂, BeH₂, BaH₂, the order of ionic character is
(a) BeH₂ < CaH₂ < BaH₂
(b) CaH₂ < BeH₂ < BaH₂
(c) BeH₂ < BaH₂ < CaH₂
(d) BaH₂< BeH₂ < CaH₂
Answer. A

Question. On heating which of the following releases CO₂ most easily?
(a) Na₂CO₃
(b) MgCO₃
(c) CaCO₃
(d) K₂CO₃
Answer. B

Question. Solubility of the alkaline earth metal sulphates in water decreases in the sequence
(a) Sr > Ca > Mg > Ba
(b) Ba > Mg > Sr > Ca
(c) Mg > Ca > Sr > Ba
(d) Ca > Sr > Ba > Mg
Answer. C

Question. Which of the following compounds has the lowest melting point?
(a) CaCl₂
(b) CaBr₂
(c) CaI₂
(d) CaF₂ 
Answer. C

Question. Which of the following alkaline earth metal sulphates has hydration enthalpy higher than the lattice enthalpy?
(a) CaSO₄
(b) BeSO₄
(c) BaSO₄
(d) SrSO₄
Answer. B

Question. Which one of the following compounds is a peroxide?
(a) KO₂
(b) BaO₂
(c) MnO₂
(d) NO₂
Answer. B

Question. Property of the alkaline earth metals that increases with their atomic number
(a) solubility of their hydroxides in water
(b) solubility of their sulphates in water
(c) ionization energy
(d) electronegativity 
Answer. A

Question. Which of the following oxides is not expected to react with sodium hydroxide?
(a) CaO
(b) SiO₂
(c) BeO
(d) B₂O₃ 
Answer. A

Question. The correct order of increasing thermal stability of K₂CO₃, MgCO₃, CaCO₃ and BeCO₃ is
(a) BeCO₃ < MgCO₃ < CaCO₃ < K₂CO₃
(b) MgCO₃ < BeCO₃ < CaCO₃ < K₂CO₃
(c) K₂CO₃ < MgCO₃ < CaCO₃ < BeCO₃
(d) BeCO₃ < MgCO₃ < K₂CO₃ < CaCO₃
Answer. A

Question. In which of the following the hydration energy is higher than the lattice energy?
(a) MgSO₄
(b) RaSO₄
(c) SrSO₄
(d) BaSO₄
Answer. A

Question. The solubility in water of sulphate down the Be group is Be > Mg > Ca > Sr > Ba. This is due to
(a) decreasing lattice energy
(b) high heat of solvation for smaller ions like Be²⁺
(c) increase in melting points
(d) increasing molecular weight. 
Answer. B

Question. All the following substances react with water. The pair that gives the same gaseous product is
(a) K and KO₂
(b) Na and Na_2O2
(c) Ca and CaH₂
(d) Ba and BaO₂. 
Answer. C

Question. Which of the following statement is false?
(a) Strontium decomposes water readily than beryllium.
(b) Barium carbonate melts at a higher temperature than calcium carbonate.
(c) Barium hydroxide is more soluble in water than magnesium hydroxide.
(d) Beryllium hydroxide is more basic than barium hydroxide. 
Answer. D

Question. In context with beryllium, which one of the following statements is incorrect?
(a) It is rendered passive by nitric acid.
(b) It forms Be2C.
(c) Its salts rarely hydrolyse.
(d) Its hydride is electron-deficient and polymeric.
Answer. C

Question. The suspension of slaked lime in water is known as
(a) lime water
(b) quick lime
(c) milk of lime
(d) aqueous solution of slaked lime. 
Answer. C

Question. The product obtained as a result of a reaction of nitrogen with CaC₂ is
(a) CaCN₃
(b) Ca₂CN
(c) Ca(CN)₂
(d) CaCN 
Answer. C

Question. Which one of the following is present as an active ingredient in bleaching powder for bleaching action?
(a) CaOCl₂
(b) Ca(OCl)₂
(c) CaO₂Cl
(d) CaCl₂ 
Answer. B

Question. Match List-I with List-II for the compositions of substances and select the correct answer using the code given :
          List-I                    List-II
(Substances)            (Composition)
(A) Plaster of Paris    (i) CaSO₄·2H₂O
(B) Epsomite             (ii) CaSO₄·1/2 H₂O
(C) Kieserite              (iii) MgSO₄·7H₂O
(D) Gypsum              (iv) MgSO₄·H₂O
                                 (v) CaSO₄
(a) (A)-(iii), (B)-(iv), (C)-(i), (D)-(ii)
(b) (A)-(ii), (B)-(iii), (C)-(iv), (D)-(i)
(c) (A)-(i), (B)-(ii), (C)-(iii), (D)-(v)
(d) (A)-(iv), (B)-(iii), (C)-(ii), (D)-(i) 
Answer. B

Question. The compound A on heating gives a colourless gas and a residue that is dissolved in water to obtain B.Excess of CO₂ is bubbled through aqueous solution of B, C is formed which is recovered in the solid form. Solid C on gentle heating gives back A. The compound is
(a) CaCO₃
(b) Na₂CO₃
(c) K₂CO₃
(d) CaSO₄·2H₂O
Answer. A

Question. Which of the following represents calcium chlorite?
(a) Ca(ClO₃)₂
(b) Ca(ClO₂)2
(c) CaClO₂
(d) Ca(ClO₄)₂
Answer. B

Question. Identify the correct statement.
(a) Plaster of Paris can be obtained by hydration of gypsum.
(b) Plaster of Paris is obtained by partial oxidation of gypsum.
(c) Gypsum contains a lower percentage of calcium than Plaster of Paris.
(d) Gypsum is obtained by heating Plaster of Paris.
Answer. C

Question. Bleaching powder is obtained by the action of chlorine gas and
(a) dilute solution of Ca(OH)₂
(b) concentrated solution of Ca(OH)₂
(c) dry CaO
(d) dry slaked lime. 
Answer. D

Question. Enzymes that utilize ATP in phosphate transfer require an alkaline earth metal (M) as the cofactor. M is
(a) Sr
(b) Be
(c) Mg
(d) Ca 
Answer. C

Question. Which of the following statements is false?
(a) Ca²⁺ ions are not important in maintaining the regular beating of the heart.
(b) Mg²⁺ ions are important in the green parts of the plants.
(c) Mg²⁺ ions form a complex with ATP.
(d) Ca²⁺ ions are important in blood clotting.
Answer. A

Question. Which of the following metal ions play an important role in muscle contraction?
(a) K⁺
(b) Na⁺
(c) Mg²⁺
(d) Ca²⁺
Answer. D

Question. Om Prakash was studying the trend of solubility of alkaline earth hydroxides in water. By doing actual experiments, he came to know that the solubility of hydroxides of alkaline earth metals in water increases down the group i.e. Be(OH)₂ is least soluble while Ba (OH)₂ maximum soluble in water. He discussed this problem with his classmate Anil. He explained the phenomenon and Om Prakash got satisfied.
(a) What explanation did Anil give to Om Prakash?
(b) What values are attached to this explanation?
(c) Ba(OH)₂ is soluble in water while BaSO₄ is almost insoluble. Give reason.

Question. During his experiments, Rajender found that sodium can be used to dry diethyl ether but not ethyl alcohol. Rajender wanted to know the reason behind it. Therefore he asked his friend Annu about this problem. Annu explained the chemistry behind it and Rajender got satisfied.
(a) What explanation did Annu gave to Rajender?
(b) Sodium is found to be more useful than potassium.
(c) What values are displayed by Annu?

Question. Quicklime is an important compound. It is prepared by thermal decomposition of limestone in tall furnaces called kiln. During such an operation the top of the Chimney of the kiln was closed. After one week when the kiln was opened it was observed that very little lime was formed. The workers reported the poor result to the Production engineer who suggested them to increase the height of the chimney. This time also there was no improvement in the production of lime. Ultimately the production Engineer approached his forms chemistry and narrated the problem. The professor suggested him to keep the top of the chimney opened. This helped.
(a) Represent the thermal decomposition of lime stone by a chemical equation.
(b) Why was the production of lime not satisfactory when the top of the chimney was closed?
(c) How did the suggestion of the professor help in the improvement of the production of lime?
(d) Mention the associated value with this incidence.

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