NEET UG Chemistry S Block Elements MCQs

Important Points

 Group-1 (alkali metals) and group-2 (alkaline earth me als) are included in the sblock elements of the periodic table. They are known like this because their oxides and hydroxides are alkaline in nature. Alkali metals possess one and alkaline earth metals possess two s-electrons. They are highly electropositive metals and form monovalent cations (M⁺) and divalent cations (M²⁺) respectively.

With the increase in atomic number, the physical and chemical properties of alkali metals show regular trend. The atomic and ionic sizes increase on going down in the group and ionization enthalpies decrease in alkali metals. The same type of trend is observed in alkaline earth metals. The first element of each of these two groups, namely, lithium in group-1 and beryllium in group-2 show similarities with the element of the next group viz. Li-Mg and Be- Al. This is called diagonal relationship. In fact, the first element of each group shows difference with other elements in the same group i.e their behaviour is anomalous. Alkali elements are bright white, soft metals melting at low temperatures. Li and Na are obtained by electrolysis. They are very active and their compounds are ionic. Their oxides and hydroxides are soluble in water and give strong alkaline solution. Amongst important compounds of sodium are sodium carbonate, sodium hydrogencarbonate, sodium hydroxide, NaOH is produced by Castner Kellner process and sodium carbonate by Solvay ammonia soda process.

The chemistry of alkaline earth metals is similar to that of alkali metals. Even then some differences are there, because the atomic and ionic sizes of alkaline earth metals decrease and the charge of the cation increases. Their oxides are less basic than those of alkali metals. 

Amongst the industrially important compounds of sodium are caustic soda, washing soda and those of calcium are calcium oxide, calcium hydroxide, plaster of Paris, calcium carbonate and Portland cement. The production of cement can be carried out by grinding the mixture of lime stone and clay and heating it in rotary kiln. The clinker obtained is mixed with gypsum (2-3%) which gives fine powder of cement. All these substances have many uses.

Monovalent sodium and potassium ions and divalent magnesium and calcium ions are found in larger proportion in biological fluid in a human being. These ions carry out important biological functions like maintenance of ionic equilibrium and nerve impulse conduction which is known as sodium-potassium pump.

M.C.Q.

(1) The alkali metals are low melting. Which of the following alkali metal is expected to melt if the room tempreature rises to 30°c ?

(a) Na (b) K (c) Rb (d) Cs

(2) The reducing power of a metal depends on various factors. Suggest the factor which makes Li, the strongest reducing agent in aqueous solution.

(a) Sublimation enthalpy (b) Ionisation enthalpy

(c) Hydration enthalpy (d) Electron - gain enthalpy

(3) Metal carbonates decompose on heating to give metal oxide and carbondioxide. Which of the metal carbonates is most stable thermally ?

(a) MgCO₃ (b) CaCO₃ (c) SrCO₃ (d) BaCO₃

(4) Which of the following metal hydroxide is the least basic ?

(a) Mg(OH)₂ (b) Ca(OH)₂ (c) Sr(OH)₂ (d) Ba(OH)₂

(5) Some of the group - 2 metal halides are covalent and soluble in organic solvents. Among the following metal halides, the one which is soluble in ethanol is ___

(a) BeCl₂ (b) MgCl₂ (c) CaCl₂ (d) SrCl₂

(6) The order of decreasing ionisation enthalpy in alkali metal is

(a) Na > Li > K > Rb (b) Li > Na > K > Rb

(c) Rb > Na > K > Li (d) K < Li < Na < Rb

(7) The solubility of metal halides depends on their nature, lattice enthalpy and hydration enthalpy of the individual ions. Among the fluorides of alkali metals, the lowest solubility of LiF in water is due to___

(a) Ionic nature of lithium fluoride (b) High lattice enthalpy

(c) High hydration enthalpy for lithium ion. (d) Low ionisation enthalpy of lithium atom.

(8) Amphoteric hydroxides react with both alkalies and acids. Which of the following Group - 2 metal hydroxides is soluble in sodium hydroxide ?

(a) Be(OH)₂ (b) Mg(OH)₂ (c) Ca(OH)₂ (d) Ba(OH)₂

(9) In the synthesis of sodium carbonate, the recovery of ammonia is done by treating NH4Cl with Ca(OH)₂.The by product obtained in this process is___

(a) NaCl (b) NaOH (c) CaCl₂ (d) NaHCO₃

(10) When sodium is dissolved in liquid ammonia, a solution of deep blue colour is obtained. The colour of the solution is due to ___

(a) sodium ion (b) ammoniated electron (c) sodium amide (d) ammoniated sodium ion

(11) By adding gypsum to cement ____

(a) setting time of cement becomes less. (b) setting time of cement increases

(c) colour of cement becomes light (d) shining surface is obtained

(12) Dead burnt plaster is ___

(a) CaSO₄ (b) CaSO₄ ×H₂O (c) CaSO₄ × ½ H₂O  (d) CaSO₄ ×2H₂O

(13) A substance which gives crimson red flame and breaks on heating to give oxygen and a brown gas is ___

(a) Magnesium nitrate (b) Calcium nitrate (c) Barium nitrate (d) Strontium nitrate

(14) The formula of sodash is ___

(a) Na₂CO₃ ×10H₂O (b) Na₂CO₃ × 2 H₂O (c) Na₂CO₃ (d) Na₂CO₃ × H₂O

(15) Which of the following compounds are readily soluble in water ?

(a) BeSO₄ (b) MgSO₄ (c) BaSO₄ (d) both (a) and (b)

(16) Identify the correct formula of halides of alkaline earth metals from the following.

(a) BaCl₂ • 2H₂O (b) BaCl₂ • 4H₂O (c) CaCl₂ • 4H₂O (d) SrCl₂ • 4H₂O

(17) Which of the following statement is true about Ca(OH)₂ ?

(a) It is used in the preparation of bleaching powder.

(b) It is a light blue solid.

(c) It does not possess disinfectant property.

(d) It is used in the manufacture of cement.

(19) When water is added to compound (A) of calcium, solution of compound (B) is formed. When CO₂ is passed into the solution, it turns milky due to the formation of compound (C). If excess of carbon dioxide is passed into the solution, milkiness disappears due to the formation of compound (D). Identify the compound (D).

(a) CaO (b) Ca(OH)₂ (c) CaCO₃ (d) Ca(HCO₃)₂

(20) Which alkali metal emits longest wavelength light in Flame test ?

(a) Na (b) K (c) Cs (d) Li

(21) Which of the following is not known ?

(a) KO₃ (b) KO₄ (c) KO₂ (d) K₂O₂

(22) Which of the following acts as reducing as well as oxidising agent ?

(a) NaNO₃ (b) Na₂O₂ (c) Na₂O (d) KNO₃

(23) The salt that is added to table salt to make it flow freely in rainy season is ___

(a) KCl (b) KI (c) Ca₃(PO₄)₂ (d) Na₃PO₄

(24) Which of the following alkaline earth metal sulphates is least soluble in water ?

(a) MgSO₄ (b) CaSO₄ (c) BaSO₄ (d) SrSO₄

(25) The hydration energy of Mg²⁺ is greater than that of ___

(a) Al³⁺ (b) Be²⁺ (c) Na⁺ (d) Mg³⁺

(26) The active constituent of bleaching powder is ___

(a) Ca(OCl)₂ (b) Ca(OCl)Cl (c) Ca(ClO₂)₂ (d) Ca(ClO₂)Cl

(27) KO₂ is used in oxygen cylinders in space and submarines because it___

(a) absorbs CO₂ and increases O₂ content (b) eliminates moisture

(c) produces ozone (d) None of the above

(28) A metal M readily forms water soluble sulphate MSO₄, water insoluble hydroxide and oxide MO which becomes inert on heating. The hydroxide is soluble in NaOH. The metal M is___

(a) Be (b) Ca (c) Mg (d) Sr

(29) Which of the following is sparingly soluble in water ?

(a) NaOH (b) KOH (c) LiOH (d) RbOH

(30) Photo electric effect is maximum in____

(a) Cs (b) K (c) Na (d) Li

(31) Among the following compounds of cement which is present in the highest amount ?

(a) Ca₂SiO₄ (b) Al₂O₃ (c) Ca₃SiO₅ (d) Ca₃Al₂O₆

(32) Which pair of the following chlorides do not impart colour to the flame ?

(a) BeCl₂ and SrCl₂ (b) BeCl₂ and MgCl₂

(c) BaCl₂ and CaCl₂ (d) MgCl₂ and CaCl₂

(33) The sequence of hydration enthalpy in following ion is ____

(a) Rb⁺ > K⁺ > Cs⁺ > Na⁺ > Li⁺ (b) Li⁺ > Na⁺ > K⁺ > Rb⁺ > Cs⁺

(c) K⁺ >Na⁺ > Rb⁺ > Cs⁺ > Li⁺ (d) Cs⁺ >Rb⁺ > K⁺ > Na⁺ > Li⁺

(34) In case of alkali metals, the covalent character increases in the order :

(a) MI > MBr > MCl < MF (b) MF < MCl < MBr < MI

(c) MBr < MCl < MI < MF (d) MF < MBr < MCl < MI

(35) Among the following the least thermally stable is ?

(a) K₂CO₃ (b) Na₂CO₃ (c) BaCO₃ (d) Li₂CO₃

(36) Which of the following oxides is amphoteric in nature ?

(a) MgO (b) BeO (c) CaO (d) BaO

(37) Which of the following characteristics is not related to alkali metals ?

(a) Their ions are iso electronic with noble gases.

(b) low melting point (c) low electronegativity (d) high ionisation energy

(38) Fill in the blanks with proper option given below for the following statement.

“All the halides of alkaline earth metals with exception of ‘‘______ ’’ are ionic in nature.”

(a) Barium halide (b) Strontium halide (c) Beryllium halide (d) Calcium halide

(39) K₂CO₃ can not be prepared by solvay ammonia process because ___

(a) K₂CO₃  is fairly soluble in water. (b) It has no water of crystallization.

(c) KHCO₃ is highly soluble in water. (d) K₂CO₃ decomposes in H₂O.

(40) The reaction of Cl₂ with X gives bleaching powder X is____

(a) CaO (b) Ca(OH)₂ (c) Ca(OCl)₂ (d) Ca(O₃Cl)₂

(41) Which of the following alkaline earth metal sulphates has hydration enthalpy higher than the lattice enthalpy ?

(a) SrSO₄ (b) MgSO₄ (c) CaSO₄ (d) BaSO₄

(42) A 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)  K₂CO₃ (c) Na₂CO₃ (d) CaSO₄ × 2H₂O

(43) For alkaline metal, which of the following trends is incorrect ?

(a) Hydration enthalpy : Be > Mg > Ca > Sr

(b) Second Ionization enthalpy: Be > Mg > Ca > Sr

(c) Density : Sr > Be > Mg > Ca

(d) Atomic size : Sr > Ca > Mg > Be

(44) Which of the following compounds is most stable ?

(a) LiCl (b) LiI (c) LiBr (d) LiF

(45) Flame test is not given by___

(a) Be (b) Sr (c) K (d) Ca

(46) The alkaline earth metals forming ionic oxides are___

(a) MgO (b) BeO (c) CaO (d) (a) and (c)

(85) The number and type of bonds between two carbon atoms in calcium carbides are ___

(a) one sigma, one pi. (b) one sigma, two pi.

(c) two sigma, one pi. (d) two sigma, two pi

 

(86) Which of the following salts are composed of isoelectronic cations and anions ?

(a) NaCl (b) MgF₂ (c) CaS (d) (b) and (c) both

 

(87) Which are correct statements for Be and Al ?

(a) Both are rendered passive by con.HNO₃

(b) Both have sp - hybridization in their compounds.

(c) Both form acidic oxides

(d) Both form hydrides

 

(88) Identify the correct statement ?

(a) Gypsum contains a lower percentage of calcium than plaster of paris

(b) Gypsum is obtained by heating plaster of paris

(c) Plaster of paris can be obtained by hydration of gypsum

(d) Plaster of paris is obtained by partial oxidation of gypsum.

 

(89) Which of the following metal is used in the test of elements in organic compounds by Lassigne test ?

(a) Li (b) Na (c) K (d) Rb

 

(90) The setting time of dicalcium silicates is ‘‘ ____’’

(a) 28 days (b) 1 year (c) 1 week (d) 24 hour

 

Assertion - Reason type Questions

 

The questions given below contains statement - 1 (Assertion) and statement - 2 (Reason) Each question has four choices (a), (b),(c) and (d) out of which only one is correct. Choose the correct option as under.

(a) Statement -1 is true, statement - 2 is true

      Statement - 2 is a correct explanation for statement - 1

(b) Statement - 1 is true, statement - 2 is true;

      Statement - 2 is not a correct explanation for statement - 1

(c) Statement - 1 is true, statement - 2 is false

(d) Statement - 1 is false, statement - 2 is true.

 

 

(102) Sylvine is the mineral of ___

(a) K (b) Na (c) Li (d) Rb

 

(103) Which pump is important in biological reaction in human body ?

(a) Ca-Mg Pump (b) K-Fe Pump (c) Na-K Pump (d) Fe-Ca Pump

 

(104) Withrite is which type of salt of Barium ?

(a) Carbonate (b) Sulphate (c) Chloride (d) Phosphate

 

(105) Silastine is the mineral of__

(a) Ca (b) Ra (c) Ba (d) Sr

 

 

 

(107) What will be final weight of 286 gm Na₂CO₃.10H₂O by Heating at 373 K ?

(a) 206 gm (b) 162 gm (c) 186 gm (d) 124 gm

 

(108) The order of decreasing polarity in the compounds CaO, CsF, KCl, MgO is

(a) CaO, CsF, KCl, MgO (b) MgO, KCl, CaO, CsF,

(c) KCl, CaO, CsF, MgO (d) CsF, KCl, CaO, MgO

 

(109) Which is not an ore of Ca ?

(a) Lime stone (b) Flurospar (c) Dolomite (d) Epsomsalt

 

(110) A certain metal is used to prepare an antacid, this metal accidently catches fire which can not be put out by using CO₂ based extiguishers. The metal is

(a) C (b) Ca (c) Mg (d) Na