🧪 Chemistry · Class 11 · NEET & JEE
s-Block Elements - Practice Questions with Answers 75 free MCQs on s-Block Elements, each with its own worked answer and explanation. Group 1 (alkali metals) and Group 2 (alkaline earth metals). Learn their reactions with water and air, important compounds like NaOH, Na₂CO₃, and CaCO₃, and anomalous behaviour of lithium and beryllium.
Take the timed s-Block Elements chapterwise test → 75 practice questions on s-Block Elements , sorted Easy → Hard. Try each one first, then open its answer page for the worked explanation. Want the full theory first? Read the s-Block Elements notes .
Flame Test Colours (s-Block Elements) Li crimson Na golden yellow K lilac/violet Ca brick red Ba apple green Each s-block metal ion emits a characteristic flame colour because heating excites electrons to higher energy levels; light is emitted as they fall back, with the colour determined by the specific energy gap.
Easy - 25 questions Q1.
Why are the alkali metals the most electropositive elements in their respective periods?
A They have low ionisation enthalpies and lose the single ns<sup>1</sup> electron easilyB They have the highest ionisation enthalpies and hold the ns<sup>1</sup> electron very tightlyC They have completely filled d-orbitalsD They gain an electron to form stable anionsShow answer & explanation →
Q2.
On moving down Group 1 from Li to Cs, the ionisation enthalpy:
A Increases steadilyB DecreasesC Remains constantD First increases then decreasesShow answer & explanation →
Q3.
Lithium, sodium and potassium are kept under kerosene, but which alkali metals are so reactive that they are stored in sealed tubes?
A Lithium and sodiumB Sodium and potassiumC Rubidium and caesiumD Lithium and potassiumShow answer & explanation →
Q4.
Which property correctly distinguishes Group 2 (alkaline earth) metals from Group 1 (alkali) metals of the same period?
A Group 2 metals are larger in atomic sizeB Group 2 metals are more electropositiveC Group 2 metals have much lower ionisation enthalpiesD Group 2 metals are harder and have higher melting pointsShow answer & explanation →
Q5.
Which alkaline earth metal and which alkali metal do NOT impart a characteristic colour to a Bunsen flame?
A Be and Mg among Group 2; none of Group 1B Be and Mg among Group 2; Li among Group 1C Ca and NaD Sr and KShow answer & explanation →
Q6.
Which groups form the s-block of the periodic table?
A Groups 1 and 2B Groups 1 to 12C Groups 17 and 18D Groups 13 to 18Show answer & explanation →
Q7.
What is the common feature of alkali metals (Group 1)?
A One valence electron (ns<sup>1</sup>)B Two valence electronsC Full d orbitalsD Zero valence electronsShow answer & explanation →
Q8.
Which metal is stored under kerosene oil to prevent reaction with air and moisture?
A SodiumB CalciumC MagnesiumD BerylliumShow answer & explanation →
Q11.
Baking soda is the common name for:
A NaHCO<sub>3</sub>B Na<sub>2</sub>CO<sub>3</sub>C NaOHD Na<sub>2</sub>SO<sub>4</sub>Show answer & explanation →
Q12.
Washing soda is:
A Na<sub>2</sub>CO<sub>3</sub>·10H<sub>2</sub>OB NaHCO<sub>3</sub>C NaOHD Na<sub>2</sub>SO<sub>4</sub>·10H<sub>2</sub>OShow answer & explanation →
Q14.
The Solvay process is used to manufacture:
A Sodium carbonate (Na<sub>2</sub>CO<sub>3</sub>)B Sodium chlorideC Sodium hydroxideD Sodium bicarbonate onlyShow answer & explanation →
Q16.
Plaster of Paris is:
A CaSO<sub>4</sub>·0.5H<sub>2</sub>O (hemihydrate)B CaSO<sub>4</sub>·2H<sub>2</sub>O, the fully hydrated gypsum formC CaCO<sub>3</sub>, common limestone before any calcinationD Ca(OH)<sub>2</sub>, ordinary slaked lime used in mortarShow answer & explanation →
Q17.
Gypsum is:
A CaSO<sub>4</sub>·2H<sub>2</sub>OB CaSO<sub>4</sub>·0.5H<sub>2</sub>OC CaCO<sub>3</sub>D Ca(OH)<sub>2</sub>Show answer & explanation →
Q21.
Which s-block element is essential for the human body as a bone constituent?
A CalciumB LithiumC RubidiumD CaesiumShow answer & explanation →
Q22.
Beryllium (Be) is anomalous among Group 2 elements because it forms:
A Covalent compounds (high charge density, small size)B Mainly ionic compounds like the rest of Group 2 typically doesC Predominantly metallic compounds rather than discrete moleculesD Stable compounds directly with noble gas elementsShow answer & explanation →
Q24.
Sodium chloride (common salt) is produced by:
A Mining rock salt or evaporation of seawaterB Electrolysis of aqueous NaOH solution in a diaphragm cellC The Solvay process used industrially to manufacture sodium carbonateD Direct combination of sodium metal with chlorine gas aloneShow answer & explanation →
Medium - 25 questions Q26.
The solubility of alkaline earth metal hydroxides increases down the group (Be(OH)<sub>2</sub> < Mg(OH)<sub>2</sub> < ... < Ba(OH)<sub>2</sub>) mainly because:
A Hydration enthalpy increases down the groupB Lattice enthalpy decreases faster than hydration enthalpy down the groupC The hydroxides become increasingly covalent and less ionic down the groupD Lattice enthalpy increases down the groupShow answer & explanation →
Q27.
When lithium, sodium and potassium are heated in excess oxygen, the principal products are respectively:
A Peroxide, superoxide and monoxideB Superoxide, monoxide and peroxideC Monoxide, peroxide and superoxideD Monoxide, superoxide and peroxideShow answer & explanation →
Q28.
Assertion: Lithium salts are mostly hydrated while other alkali-metal salts are usually anhydrous. Reason: Li<sup>+</sup> has the largest charge-to-size ratio among alkali-metal ions.
A The assertion is false but the reason is trueB Both statements are true but the reason does not correctly explain the assertionC The assertion is true but the reason is falseD Both assertion and reason are true and the reason explains the assertionShow answer & explanation →
Q29.
The thermal stability of the carbonates of Group 2 follows the order BeCO<sub>3</sub> < MgCO<sub>3</sub> < CaCO<sub>3</sub> < SrCO<sub>3</sub> < BaCO<sub>3</sub> because, down the group:
A The cation polarises the carbonate ion less, stabilising itB The cation becomes smaller and far more strongly polarisingC Lattice enthalpy increases sharplyD The carbonate ion becomes more covalentShow answer & explanation →
Q30.
Which observation is a direct consequence of the diagonal relationship between lithium and magnesium?
A Both form highly soluble carbonatesB Both form nitrides with N<sub>2</sub> and carbonates that decompose on heatingC Both form stable solid hydrogencarbonatesD Both impart a characteristic crimson colour to the Bunsen flameShow answer & explanation →
Q31.
The anomalous behaviour of lithium compared to other alkali metals is due to:
A Very small size and high charge density (diagonal relationship with Mg)B Its position as the most chemically reactive metal in Group 1C Its unusually low electronegativity compared to the rest of Group 1D Its status as the heaviest element within Group 1Show answer & explanation →
Q32.
Down Group 1, which property decreases?
A First ionisation energyB Atomic radiusC DensityD Reactivity with waterShow answer & explanation →
Q33.
Lithium forms a nitride directly with N<sub>2</sub> because:
A Li ions are small, and Li<sub>3</sub>N has high lattice energy (similar to Mg)B Lithium is simply the most reactive metal within the alkali metal familyC Lithium has the highest first ionisation energy among the alkali metalsD Lithium displays amphoteric behaviour unlike the other alkali metalsShow answer & explanation →
Q34.
The Castner-Kellner process produces NaOH and Cl<sub>2</sub> by:
A Electrolysis of brine (NaCl solution) using mercury cellB The Solvay process, which instead yields sodium carbonate from brineC Electrolysis of molten anhydrous NaCl to give metallic sodiumD Direct reaction of sodium carbonate with slaked limeShow answer & explanation →
Q35.
Cement is mainly composed of:
A CaO·SiO<sub>2</sub>·Al<sub>2</sub>O<sub>3</sub> (calcium aluminosilicate)B Pure CaCO<sub>3</sub> with no other mineral components presentC Ca(OH)<sub>2</sub> alone, used directly without further processingD CaSO<sub>4</sub>, the same hemihydrate used in plaster of ParisShow answer & explanation →
Q36.
Setting of plaster of Paris involves:
A Rehydration: CaSO<sub>4</sub>·0.5H<sub>2</sub>O + 1.5H<sub>2</sub>O → CaSO<sub>4</sub>·2H<sub>2</sub>O (gypsum)B Dehydration of the hemihydrate to anhydrous calcium sulfateC Oxidation of the sulfate ion to a higher oxidation stateD Reduction of calcium sulfate to elemental calcium and sulfurShow answer & explanation →
Q37.
Which reaction represents the preparation of Na from NaCl?
A Electrolysis of molten NaCl (Down's process)B Chemical reduction with carbon under usual circumstancesC Reaction with water according to most researchersD Solvay process in the majority of cases studiedShow answer & explanation →
Q38.
Milk of lime is a suspension of Ca(OH)<sub>2</sub> in water. Its use in industry includes:
A Water treatment, mortar, sugar purificationB Manufacturing soap through saponification of fatsC Manufacturing glass by fusing silica with soda ashD Industrially producing ammonia from nitrogen and hydrogenShow answer & explanation →
Q39.
Potassium superoxide (KO<sub>2</sub>) is used in:
A Self-contained breathing apparatus (reacts with CO<sub>2</sub> and H<sub>2</sub>O to release O<sub>2</sub>)B Nitrogen-based fertilisers applied directly to soil as widely reportedC Explosive formulations requiring a stable oxidiser in standard practiceD Soap manufacture through reaction with fatty acids under most conditions encounteredShow answer & explanation →
Q40.
Magnesium burns in CO<sub>2</sub> because:
A Mg reduces CO<sub>2</sub> to C (2Mg + CO<sub>2</sub> → 2MgO + C), so CO<sub>2</sub> extinguishers fail on Mg firesB Magnesium is actually less reactive than carbon toward oxygen as frequently observed in practiceC Magnesium generally does not burn when exposed to CO<sub>2</sub> in many documented casesD The reaction instead produces stable magnesium carbonate, MgCO<sub>3</sub> according to conventional understandingShow answer & explanation →
Q41.
The Solvay process steps include: salt + ammonia + CO<sub>2</sub> → NaHCO<sub>3</sub> (precipitate) → heating → Na<sub>2</sub>CO<sub>3</sub>. The ammonia is:
A Recovered and recycled by treating NH<sub>4</sub>Cl with Ca(OH)<sub>2</sub>B Discharged entirely as waste gas at the end of the processC Permanently consumed and converted into sodium bicarbonateD Reduced back to elemental nitrogen gas for disposalShow answer & explanation →
Q42.
Which alkaline earth metal is used in making strong lightweight alloys for aircraft?
A Magnesium (Mg)B Calcium (Ca)C Beryllium (Be)D Barium (Ba)Show answer & explanation →
Q43.
Thermal stability of Group 2 carbonates:
A Increases down the group (larger cations have lower charge density, stabilise CO<sub>3</sub><sup>2-</sup> more)B Decreases steadily down the group as the cation's charge density falls in routine practiceC Remains essentially identical across most Group 2 carbonate salt overall in most casesD Depends mainly on the external storage temperature, not on cation size under typical conditionsShow answer & explanation →
Q44.
Hard water deposit (scale) in boilers is removed using:
A Calgon (sodium hexametaphosphate) or HCl treatmentB Concentrated NaOH solution flushed through the boilerC Additional hard water poured in to dissolve existing scaleD Simply boiling the water further without any added reagentShow answer & explanation →
Q45.
Chlorophyll (the green plant pigment) contains which metal from the s-block?
A Magnesium (Mg<sup>2+</sup> at the porphyrin centre)B Calcium, coordinated at the centre of the porphyrin ringC Sodium, held loosely at the centre of the porphyrin structureD Barium, chelated within the porphyrin macrocycleShow answer & explanation →
Q46.
Epsom salt is:
A MgSO<sub>4</sub>·7H<sub>2</sub>OB CaSO<sub>4</sub>·2H<sub>2</sub>OC BaSO<sub>4</sub>D Na<sub>2</sub>SO<sub>4</sub>·10H<sub>2</sub>OShow answer & explanation →
Q47.
The flame colours of alkali metals are caused by:
A Electrons jumping from excited states back to ground state emitting visible lightB Small-scale nuclear reactions occurring within the heated metal according to standard textbooksC The colour of the gaseous combustion products formed in the flame in general practiceD Simple ionic dissociation of the metal salt in the flame as frequently describedShow answer & explanation →
Q48.
Barium sulfate (BaSO<sub>4</sub>) is used as an X-ray contrast agent for the digestive tract because:
A It is insoluble and non-toxic, opaque to X-raysB It is highly soluble, allowing rapid absorption into the bloodstreamC It functions as an essential dietary nutrient for digestionD It readily dissolves upon contact with stomach acidShow answer & explanation →
Q49.
Radium (Ra) was discovered by:
A Marie and Pierre CurieB Humphry Davy in most textbook accountsC Mendeleev during normal conditionsD Moseley as generally observedShow answer & explanation →
Q50.
Beryllium cannot be obtained by electrolysis of aqueous BeCl<sub>2</sub> solution because:
A Be is above H in activity series; H<sub>2</sub> is discharged preferentially at the cathodeB Beryllium's melting point is generally too high for aqueous electrolysis as widely reportedC Beryllium chloride's covalent bonding prevents it from dissolving in waterD Beryllium is a radioactive element unsuitable for aqueous processing in standard practiceShow answer & explanation →
Hard - 25 questions Q51.
Although Li has the most negative standard electrode potential (E° = -3.04 V), it reacts with water less vigorously than sodium. The reason is that:
A Lithium has a far lower ionisation enthalpy and so reacts much more gently than sodiumB Sodium is more electropositive than lithiumC High hydration energy makes E° very negative, but a high melting point slows the reactionD Lithium does not react with water at allShow answer & explanation →
Q52.
In the Solvay (ammonia-soda) process, which statement correctly explains why it cannot be used to manufacture potassium carbonate?
A Potassium does not form a carbonateB KCl is insoluble in waterC Ammonia does not react with potassium salts to form carbonatesD Potassium hydrogencarbonate (KHCO<sub>3</sub>) is too soluble to precipitate outShow answer & explanation →
Q53.
Beryllium chloride is a covalent compound that is polymeric in the solid state. In the solid polymer, each beryllium atom is:
A Tetrahedrally four-coordinate through chloride bridgesB Linearly two-coordinate via sp hybridisation as in the vapour phaseC Octahedrally six-coordinateD Trigonal planar three-coordinateShow answer & explanation →
Q54.
A blue solution of sodium in liquid ammonia conducts electricity and is strongly reducing. On standing, the blue colour fades and the conductivity changes because:
A Sodium metal precipitates out unchangedB Ammoniated electrons slowly convert to sodium amide with evolution of dihydrogenC The dissolved sodium is slowly oxidised to sodium hydroxide and nitrogen gasD Ammonia is oxidised to nitrogen gasShow answer & explanation →
Q55.
Lithium iodide is the most covalent of the lithium halides. According to Fajans' rules this is because, compared with the other halides:
A Lithium iodide has the highest lattice enthalpy of all the halidesB The iodide ion has the highest chargeC The iodide ion is large and most easily polarised by the small Li<sup>+</sup>D The iodide ion is the least polarisable anionShow answer & explanation →
Q56.
The lattice energy of NaF is higher than NaCl because:
A F- is smaller than Cl-, so Na-F distance is shorter and lattice energy (alpha 1/r) is higherB Fluoride ion generally has a lower atomic mass than chloride ion under typical conditionsC Sodium ion is somehow larger when paired specifically with fluoride according to standard textbooksD NaF possesses significant covalent character unlike NaCl in general practice as frequently describedShow answer & explanation →
Q57.
Why does LiF have lower solubility in water than LiCl?
A LiF has very high lattice energy; the hydration enthalpy does not overcome itB LiF is a mainly covalent compound that resists hydration largely in most textbook accountsC LiCl carries a noticeably higher degree of bond polarity than LiF during normal conditionsD LiF exists as a volatile gas under standard room conditions as generally observedShow answer & explanation →
Q58.
Why does Na react vigorously with water while Li reacts less vigorously?
A Na has lower first ionisation energy than Li, making it easier to ionise; also Na reacts exothermically fasterB Lithium is generally a noticeably more electronegative element than sodium in typical laboratory settingsC Lithium's higher melting point reduces the metal surface area exposed to water under usual circumstancesD Sodium atoms contain fewer total orbital electrons than lithium atoms do according to most researchers in the majority of cases studiedShow answer & explanation →
Q59.
In the Down's process, CaCl<sub>2</sub> is added to NaCl to:
A Lower the melting point from 800°C to ~600°C making electrolysis practicalB Simply raise the ionic conductivity without affecting melting pointC Form a protective layer that prevents oxidation of the sodium productD Serve as a catalyst that speeds the electrode reactionsShow answer & explanation →
Q60.
Organolithium compounds (RLi) are more reactive than Grignard reagents (RMgX) because:
A C-Li bonds are more covalent and have more ionic character; Li is more electropositive than MgB Lithium is generally a noticeably heavier element than magnesium overall as widely reportedC RLi compounds exist as largely ionic crystalline salts dissolved in solution in standard practiceD Magnesium is a more electronegative element than lithium in these compounds under most conditions encounteredShow answer & explanation →
Q61.
The hardness order of Group 2 metals is:
A Be > Mg > Ca > Sr > Ba (decreases down the group as metallic bonding weakens)B Ba > Sr > Ca > Mg > Be, increasing steadily down the group as frequently observed in practiceC All five Group 2 metals show essentially identical hardness in many documented casesD Hardness is determined mainly by ambient temperature, not atomic size according to conventional understandingShow answer & explanation →
Q62.
Which Group 1 element has an anomalously high melting point compared to trend?
A Lithium (180°C vs Na 98°C, K 63°C, Rb 39°C, Cs 28°C)B Sodium, which melts unexpectedly higher than the rest of the groupC Caesium, despite being the heaviest common alkali metalD Rubidium, despite sitting between potassium and caesiumShow answer & explanation →
Q63.
Diagonal relationship between Li and Mg: which specific property is shared?
A Both form nitrides (Li<sub>3</sub>N and Mg<sub>3</sub>N<sub>2</sub>), have similar solubility trends, and form covalent organometallic compoundsB Both generally exist as ordinary solid metals under standard everyday room conditions in routine practiceC Lithium uniquely possesses exactly two valence electrons in its single outer shell overall in most cases under typical conditionsD Both metals react with plain cold water at exactly the same observable vigorous rate according to standard textbooksShow answer & explanation →
Q65.
When excess Na<sub>2</sub>O<sub>2</sub> reacts with water, the products are:
A NaOH and H<sub>2</sub>O<sub>2</sub> (2Na<sub>2</sub>O<sub>2</sub> + 2H<sub>2</sub>O → 4NaOH + O<sub>2</sub>)B Na<sub>2</sub>O and oxygen gas released without any hydroxide formedC NaOH alone, with no oxygen or peroxide byproduct at allD Na<sub>2</sub>CO<sub>3</sub> and hydrogen peroxide formed via carbonationShow answer & explanation →
Q66.
Calcium carbide (CaC<sub>2</sub>) reacts with water to give:
A Acetylene (C<sub>2</sub>H<sub>2</sub>) and Ca(OH)<sub>2</sub>B Ethylene and CaO in general practiceC CO<sub>2</sub> and Ca(OH)<sub>2</sub> as frequently describedD CO and CaCO<sub>3</sub> in most textbook accountsShow answer & explanation →
Q67.
Liquid ammonia is used as a solvent in which Group 1 reactions?
A Dissolution of alkali metals in liquid NH<sub>3</sub> to give blue solutions (solvated electrons)B The direct formation of sodium peroxide from sodium metal and oxygen during normal conditionsC The electrolytic reduction of molten calcium chloride to calcium metal as generally observedD The Solvay process used to manufacture sodium carbonate in typical laboratory settingsShow answer & explanation →
Q68.
The blue colour of alkali metal solutions in liquid ammonia is due to:
A Solvated electrons (e-(am)) absorbing light in the visible rangeB Sodium cations themselves absorbing visible light in solutionC Liquid ammonia itself possessing an inherent blue colourD Trace amounts of dissolved sodium oxide colouring the solutionShow answer & explanation →
Q69.
In which reaction is barium peroxide (BaO<sub>2</sub>) an important intermediate?
A Historical preparation of H<sub>2</sub>O<sub>2</sub>: BaO<sub>2</sub> + H<sub>2</sub>SO<sub>4</sub> → BaSO<sub>4</sub> + H<sub>2</sub>O<sub>2</sub>B The electrolytic production of elemental barium metalC The direct chemical reduction of barium sulfate to barium sulfideD The industrial Solvay process for manufacturing sodium carbonateShow answer & explanation →
Q70.
The standard electrode potential E° of Li/Li+ (-3.05 V) is more negative than Na/Na+ (-2.71 V). In terms of reactivity in water, however:
A Na reacts more vigorously with water than Li, despite Li's more negative E°, due to kinetic factorsB Lithium instead reacts noticeably faster with water than sodium does in practiceC Both metals react with cold water at an identical and equally vigorous observable rateD The standard electrode potential value alone fully and accurately predicts the reaction rateShow answer & explanation →
Q71.
Beryllium forms BeF<sub>2</sub> with a structure resembling:
A SiO<sub>2</sub> (polymeric tetrahedral network via bridging F atoms in solid state)B NaCl, adopting a simple ionic rock-salt lattice under usual circumstancesC BF<sub>3</sub>, existing as a discrete trigonal planar molecule according to most researchersD A simple discrete molecule with little extended network in the majority of cases studiedShow answer & explanation →
Q72.
Why is BeSO<sub>4</sub> more soluble in water than BaSO<sub>4</sub>?
A Be<sup>2+</sup> has high charge density and large hydration enthalpy that overcomes the lattice energy; Ba<sup>2+</sup> is large with lower hydration enthalpyB BeSO<sub>4</sub> generally happens to possess a much lower overall lattice energy than BaSO<sub>4</sub> does in the crystal as widely reported in standard practiceC BaSO<sub>4</sub> supposedly carries a noticeably greater degree of ionic character than the corresponding beryllium salt under most conditions encounteredD Ba<sup>2+</sup> is actually claimed to be a far more strongly polarising cation than the small, dense Be<sup>2+</sup> ion as frequently observed in practiceShow answer & explanation →
Q73.
The Solvay process cannot economically produce potassium carbonate (K<sub>2</sub>CO<sub>3</sub>) because:
A KHCO<sub>3</sub> is too soluble in the brine solution to precipitate out as NaHCO<sub>3</sub> doesB Potassium chloride is generally too expensive to use as a raw materialC Potassium metal reacts dangerously with the carbon dioxide feedstock in many documented casesD K<sub>2</sub>CO<sub>3</sub> decomposes readily under the mild conditions of the process according to conventional understandingShow answer & explanation →
Q74.
Sodium amalgam (Na/Hg) is used as a reducing agent. The amalgam forms because:
A Na dissolves in mercury forming a liquid alloy (amalgam) that is safer and less reactive than pure NaB Sodium chemically reacts with mercury to form a distinct crystalline ionic compound in routine practiceC Mercury metal directly oxidises the sodium as the two substances come into contact overall in most casesD Sodium and mercury are actually largely immiscible and rarely form an alloy under typical conditionsShow answer & explanation →
Q75.
Why does group 2 hydroxides become more basic and more soluble down the group?
A Increasing cation size reduces lattice energy and increases hydration enthalpy advantage; larger M<sup>2+</sup> also holds OH- less tightlyB The atomic mass of each successive Group 2 metal supposedly decreases steadily down the group according to standard textbooksC The electronegativity of the metal supposedly increases steadily down the group toward fluorine-like values in general practiceD The first ionisation energy of the metal supposedly increases steadily down the group instead of falling as frequently describedShow answer & explanation →