The addition of dilute $NaOH$ to $C{r^{3 + }}$ salt solution will give

a solution of ${[Cr{(OH)_4}]^ - }$

Precipitate of ${[Cr{(OH)_6}]^{3 - }}$

${\rm{Ba}}{\left( {{\rm{OH}}} \right)_2}$

Magnesium wire burns in the atmosphere of ${\rm{C}}{{\rm{O}}_2}$ because:

Magnesium acts as an oxidizing agent

Magnesium has 2 electrons in the outermost orbit

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JEE • CHEMISTRY • S-BLOCK ELEMENTS

S-block elements practice · Medium

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These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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Showing 1-30 of 151 questions

1 Medium

1 of 151

Analyzing +4 | -1

Assertion (A): Among the alkali metals, lithium salts exhibit the least electrical condutance in aqueous solutions.
Reason (R): Smaller the radius of the hydrated cation, lower is the electrical conductance in aqueous solutions.

View answer and explanation

Correct option: C

\mathbf{A}

is true but

\mathbf{R}

is false.

Option C is correct because Assertion (A) is true, lithium salts have the least electrical conductance, but Reason (R) is false, as smaller hydrated radius implies higher conductance.

2 Medium

2 of 151

Analyzing +4 | -1

(A)

is a ternary salt with divalent cation.

(A)

gives yellow ppt. with

\mathrm{K}_2 \mathrm{CrO}_4

as well as with

\mathrm{AgNO}_3

. (A) is precipitated by

\mathrm{H}_2 \mathrm{~S}

neither in acidic nor ammoniacal medium, but addition of

\left(\mathrm{NH}_4\right)_2 \mathrm{CO}_3

\mathrm{NH}_4 \mathrm{OH}

gave white ppt. (B).

0.297 \mathrm{~g}

(A)

gave

0.197 \mathrm{~g}

(B)

. Identify

(A)

View answer and explanation

Correct option: A

\mathrm{BaBr}_2

The correct answer is A (

\mathrm{BaBr}_2

) because it satisfies the given conditions of forming yellow precipitates with

\mathrm{K}_2 \mathrm{CrO}_4

and

\mathrm{AgNO}_3

, and forming a white precipitate with

(\mathrm{NH}_4)_2 \mathrm{CO}_3

\mathrm{NH}_4 \mathrm{OH}

3 Medium

3 of 151

Remembering +4 | -1

Which of the alkali metal is having least melting point?

View answer and explanation

Correct option: D

Option D (Cs) is correct because melting point decreases down the group in alkali metals due to increasing atomic size and weaker metallic bonding.

4 Medium

4 of 151

Analyzing +4 | -1

Statement 1:

{LiCl}

is predominatly a covalent compound.

Statement 2: Electronegativity difference between

{Li}

and

{Cl}

is too small.

View answer and explanation

Correct option: A

Statement 1 is true but statement 2 is false

The correct answer is A (Statement 1 is true but statement 2 is false) because LiCl has significant covalent character due to the high polarizing power of Li+ ion, despite the electronegativity difference.

5 Medium

5 of 151

Analyzing +4 | -1

Metal

({M})+

air

\stackrel{\Delta}{\rightarrow}({A}) \stackrel{{H}_2 {O}}{\longrightarrow}({B}) \stackrel{{HCl}}{\longrightarrow}

white fumes. Metal

{M}

can be

View answer and explanation

Correct option: A

{Li}, {Mg}

{Al}

Option A (

{Li}, {Mg}

{Al}

) is correct because these metals can form nitrides that hydrolyze to produce ammonia, which reacts with HCl to form white fumes of ammonium chloride.

6 Medium

6 of 151

Understanding +4 | -1

Among the alkali metals caesium is the most reactive because

View answer and explanation

Correct option: D

The outermost electron is more loosely bound than the outermost electron of the other alkali metals.

Option D is correct because caesium's outermost electron is the most loosely bound due to its large atomic size, making it the most reactive alkali metal.

7 Medium

7 of 151

Understanding +4 | -1

Nitrates of which of the following alkali metals decomposes on heating to give corresponding oxide?

View answer and explanation

Correct option: A

{Li}

Option A (

{Li}

) is correct because lithium nitrate decomposes to give lithium oxide, while other alkali metal nitrates decompose to give nitrites.

8 Medium

8 of 151

Understanding +4 | -1

Which of the following is not correct?

View answer and explanation

Correct option: A

2Li_2O \underset{673 \mathrm{~K}}{\stackrel{\text { heat }}{\longrightarrow}}Li_2O_2+2Li

Option A (

2Li_2O \underset{673 \mathrm{~K}}{\stackrel{\text { heat }}{\longrightarrow}}Li_2O_2+2Li

) is not correct because Lithium primarily forms the monoxide (

Li_2O

) and does not readily form the peroxide (

Li_2O_2

9 Medium

9 of 151

Remembering +4 | -1

Which alkaline earth metal shows some anomalous behaviour and has the same electronegativity as aluminium?

View answer and explanation

Correct option: D

\mathrm{Be}

Option D (

\mathrm{Be}

) is correct because Beryllium (Be) shows anomalous behavior due to its small size and high polarizing power, and it has a similar electronegativity to aluminium.

10 Medium

10 of 151

Understanding +4 | -1

The addition of dilute

NaOH

C{r^{3 + }}

salt solution will give

View answer and explanation

Correct option: B

Precipitate of

C{r_2}{O_3}{({H_2}O)_n}

Option B (Precipitate of

C{r_2}{O_3}{({H_2}O)_n}

) is correct because the addition of dilute NaOH to a Cr3+ salt solution results in the precipitation of hydrated chromium(III) oxide.

11 Medium

11 of 151

Understanding +4 | -1

Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) Lithium salts are hydrated.
Reason (R) Lithium has higher polarising power than other alkali metal group members.
In the light of the above statements, choose the most appropriate answer from the options given below.

View answer and explanation

Correct option: A

Both (A) and (R) are true but (R) is not the correct explanation of (A).

Option A (Both (A) and (R) are true but (R) is not the correct explanation of (A)) is correct because while both the assertion and reason are true, the reason doesn't directly explain why lithium salts are hydrated.

12 Medium

12 of 151

Remembering +4 | -1

Choose the correct order of density of the alkali metals.

View answer and explanation

Correct option: A

\mathrm{Li}<\mathrm{K}<\mathrm{Na}<\mathrm{Rb}<\mathrm{Cs}

Option A (

\mathrm{Li}<\mathrm{K}<\mathrm{Na}<\mathrm{Rb}<\mathrm{Cs}

) is the correct order of density for alkali metals, considering the anomaly between Na and K.

13 Medium

13 of 151

Remembering +4 | -1

Portland cement does not contain:

View answer and explanation

Correct option: D

C{a_3}{(P{O_4})_2}

Option D (

Ca_3(PO_4)_2

) is correct because Portland cement primarily consists of calcium silicates and aluminates, and does not contain calcium phosphate.

14 Medium

14 of 151

Analyzing +4 | -1

\text{(Mily Cloud) } {C} \stackrel{{CO}_2}{\longleftarrow} {A}+{Na}_2 {CO}_3 \rightarrow {B}+{C}

The chemical formulae of

{A}

and

{B}

are

View answer and explanation

Correct option: B

{Ca}({OH})_2

and

{NaOH}

Option B (

{Ca}({OH})_2

and

{NaOH}

) is correct because calcium hydroxide reacts with carbon dioxide to form calcium carbonate (milky cloud) and with sodium carbonate to form calcium carbonate and sodium hydroxide.

15 Medium

15 of 151

Understanding +4 | -1

Select the correct statements

(i)

\mathrm{Cs}^{+}

is more highly hydrated that the other alkali metal ions

(ii) Among the alkali metals

\mathrm{Li}, \mathrm{Na}, \mathrm{K}

and

\mathrm{Rb}

, lithium has the highest melting point

(iii) Among the alkali metals only lithium forms a stable nitride by direct combination with nitrogen

View answer and explanation

Correct option: D

(ii) and (iii)

Option D ((ii) and (iii)) is correct because Li+ is more hydrated, Li has the highest melting point among alkali metals, and only Li forms a stable nitride.

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16 Medium

16 of 151

Analyzing +4 | -1

Which of the following is not correct as indicated?

View answer and explanation

Correct option: C

Li\mathrm{ \,\,and }\,\,Na

do not impart colour in oxidizing flame

Option C is correct because ethylene undergoes Sabatier and Senderen's reaction (catalytic hydrogenation) but does not react with ammoniacal silver nitrate.

17 Medium

17 of 151

Remembering +4 | -1

Alkali metals when dissolved in liquid

{NH}_3

at very high concentration gives which of the following coloured solution?

View answer and explanation

Correct option: C

Bronze

Option C (Bronze) is correct because at high concentrations, alkali metals dissolved in liquid ammonia form metal clusters, leading to a bronze-colored solution.

18 Medium

18 of 151

Analyzing +4 | -1

An inorganic compound first melts then resolidifies and then liberates a gas. It may be:

View answer and explanation

Correct option: A

KCl{O_3}

KClO3 first melts upon heating, then decomposes into KCl (a solid) and O2 (a gas).

19 Medium

19 of 151

Remembering +4 | -1

Baryta is:

View answer and explanation

Correct option: A

\mathrm{BaO}

Option A (

\mathrm{BaO}

) is correct because Baryta is the common name for barium oxide, which has the chemical formula

\mathrm{BaO}

20 Medium

20 of 151

Understanding +4 | -1

Magnesium wire burns in the atmosphere of

\mathrm{C}{\mathrm{O}_2}

because:

View answer and explanation

Correct option: C

Magnesium acts as a reducing agent and removes oxygen from

\mathrm{C}{\mathrm{O}_2}

Option C is correct because magnesium acts as a reducing agent, removing oxygen from

\mathrm{C}{\mathrm{O}_2}

due to its higher reducing power than carbon.

21 Medium

21 of 151

Understanding +4 | -1

Which of the following statement is false?

View answer and explanation

Correct option: D

\mathrm{Na}^{+}

ions are the most abundant cations within cell fluids

Option D is the false statement.

\mathrm{K}^+

ions, not

\mathrm{Na}^+

ions, are the most abundant cations within cell fluids.

22 Medium

22 of 151

Understanding +4 | -1

Sodium thiosulphate is formed when:

View answer and explanation

Correct option: C

\mathrm{N}{\mathrm{a}_2}\mathrm{S}{\mathrm{O}_3}

is boiled with

\mathrm{N}{\mathrm{a}_2}\mathrm{S}

and

{\mathrm{I}_2}

Option C (

\mathrm{N}{\mathrm{a}_2}\mathrm{S}{\mathrm{O}_3}

is boiled with

\mathrm{N}{\mathrm{a}_2}\mathrm{S}

and

{\mathrm{I}_2}

) is correct because sodium thiosulphate is formed by the reaction of sodium sulfite with sodium sulfide in the presence of iodine.

23 Medium

23 of 151

Analyzing +4 | -1

A: Among alkali metals, Lithium is the strongest reducing agent.

R:

\mathrm{Li}^{+}

ions are heavily hydrated in water and large amount of hydration energy helps in the release of electrons from

\mathrm{Li}

atoms.

View answer and explanation

Correct option: A

Both (A) and (R) are correct and (R) is the correct explanation of (A)

Option A is correct because Lithium is indeed the strongest reducing agent among alkali metals, and this is due to the high hydration energy of Li+ ions.

24 Medium

24 of 151

Analyzing +4 | -1

{BeSO}_4

and

{MgSO}_4

decompose on heating.

R: Lattice structures are not stable when anions and cations are not of comparable size.

View answer and explanation

Correct option: A

Both A and R are true and R is the correct explanation of A

Option A is correct because BeSO4 and MgSO4 decompose due to the large difference in size between the cation and anion, leading to lower lattice energy.

25 Medium

25 of 151

Analyzing +4 | -1

Statement 1: Lithium is the weakest reducing agent among alkali metals.

Statement 2: In alkali metals I.P. decreases down the group.

View answer and explanation

Correct option: B

Statement 1 is false but statement 2 is true

Option B (Statement 1 is false but statement 2 is true) is correct because Lithium is the strongest reducing agent in aqueous solution due to its high hydration energy, and ionization energy decreases down the group.

26 Medium

26 of 151

Analyzing +4 | -1

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R.
Assertion A : LiF is sparingly soluble in water.
Reason R : The ionic radius of

L{i^ + }

ion is smallest
among its group members, hence has least
hydration enthalpy.
In the light of the above statements, choose the
most appropriate answer from the options given
below.

View answer and explanation

Correct option: C

A is true but R is false.

Option C (A is true but R is false) is correct because LiF is sparingly soluble due to high lattice enthalpy, and

Li^+

has high hydration enthalpy due to its small size.

27 Medium

27 of 151

Understanding +4 | -1

The compound insoluble in acetic acid is:

View answer and explanation

Correct option: D

Calcium oxalate

Option D (Calcium oxalate) is correct because calcium oxalate is known to be insoluble in acetic acid.

28 Medium

28 of 151

Understanding +4 | -1

A{l_2}\,{O_3}\,

was leached with alkali to get

X.

the solution of

X

on passing of gas

Y,

forms

Z.

X,\,\,Y

and

Z

respectively are

View answer and explanation

Correct option: D

X = Na\left[ {Al{{\left( {OH} \right)}_4}} \right],Y = C{O_2},\,\,\,\,Z = A{l_2}{O_3} \cdot x{H_2}O\,\,

Option D (

X = Na[Al(OH)_4], Y = CO_2, Z = Al_2O_3 \cdot xH_2O

) is correct because aluminum oxide reacts with alkali to form sodium aluminate, which then reacts with carbon dioxide to form hydrated aluminum oxide.

29 Medium

29 of 151

Understanding +4 | -1

Calgon is used for water treatment. Which of the following statement is not true about Calgon?

View answer and explanation

Correct option: A

Calgon contains the 2nd most abundant element by weight in the Earth’s crust.

Option A is the correct answer because Calgon is a compound, not an element, and therefore cannot *contain* the 2nd most abundant element. The 2nd most abundant element in Earth's crust is Silicon.

30 Medium

30 of 151

Analyzing +4 | -1

Assertion (A): Group 1 elements are the largest in their horizontal periods in the periodic table (exclude noble gases).

Reason (R): The melting and boiling points of group 1 elements increases on moving down from

Li

Cs

View answer and explanation

Correct option: C

Assertion (A) is true, and Reason (R) is false.

Option C (Assertion (A) is true, and Reason (R) is false) is correct because Group 1 elements are indeed the largest in their respective periods (excluding noble gases), but the melting and boiling points of Group 1 elements decrease, not increase, down the group from Li to Cs.

Revision notes and key takeaways

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Key Takeaways

✓ This set contains 151 single-correct-answer MCQs on S-BLOCK ELEMENTS.
✓ Try each question before opening its answer. Read the explanation where one is available.
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