MCQ Questions for Class 11 Medical Chemistry The S-Block Elements Quiz 13

Which of the following compounds is (are) not soluble in water?

0%
$Li_{2}CO_{3}$
0%
$LiF$
0%
$Li_{3}PO_{4}$
0%
$All\ of\ these$

Which of the following species does not exist under normal conditions?

0%
$Be_2^+$
0%
$Be_2$
0%
$B_2$
0%
$Li_2$

Explanation

$Bond$

$order$ =

$1/2[\space Number\space of\space electrons\space in\space bonding\space orbital\space -\space Number\space of\space electrons\space in\space antibonding\space orbitals\space]$

$Bond$

$order$ =

$1/2$ [

$N_b$ -

$N_a$ ]

(i)

$Be_2^+$ :

Total valence electrons = 7

$Configuration$ :

$[ \sigma(1s^2)\sigma^*(1s^2)\sigma(2s^2)\sigma^*(2s^1)]$

$Bond$

$order$ =

$1/2[4-3]$ = 0.5

$Be_2^+$ exist under normal condition.

(ii)

$Be_2$ :

Total valence electrons = 8

$Configuration$ :

$[ \sigma(1s^2)\sigma^*(1s^2)\sigma(2s^2)\sigma^*(2s^2)]$

$Bond$

$order$ =

$1/2[4-4]$ = 0

$Be_2$ does not exist.

(iii)

$B_2$ :

Total valence electrons = 10

$Configuration$ :

$[ \sigma(1s^2)\sigma^*(1s^2)\sigma(2s^2)\sigma^*(2s^2)\pi(2p_x^1)\pi(2p_y^1)]$

$Bond$

$order$ =

$1/2[6-4]$ = 1

$B_2$ is a stable molecule.

(iv)

$Li_2$ :

Total valence electrons = 6

$Configuration$ :

$[\sigma(1s^2)\sigma^*(1s^2)\sigma(2s^2)]$

$Bond$

$order$ =

$1/2[4-2]$ = 1

$Li_2$ is a stable molecule.

Hence the correct option is (B).

Which of the following increases in magnitude as the atomic number of alkali metals increases?

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Electronegativity
0%
First ionisation potential
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Ionic radius
0%
Melting point

Which of the following compound is used in gun powder?

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$LiNO_{3}$
0%
$NaNO_{3}$
0%
$Pb(NO_{3})_{2}$
0%
$KNO_{3}$

Sodium is heated in air at

$350^oC$ to form

$X, X$ absorbs

$CO_2$ and forms sodium carbonate and

$Y$ . Which of the following is

$Y$ ?

0%
$H_2$
0%
$O_2$
0%
$H_2O_2$
0%
$O_3$

Match the compounds given in

$(X)$ with their uses in

$(Y)$

	$X$		$Y$
A.	$NaOH$	1.	Glass
B.	$Na_{2}S_{2}O_{3}$	2.	Germicide
C.	$NaCN$	3.	Antichlor
D.	$Na_{2}CO_{3}$	4.	Soap

0%
$A (4), B(3), C(2), D(1)$
0%
$A (3), B (4), C(1), D(2)$
0%
$A(2), B(3), C(4), D(1)$
0%
$A(1), B(2), C(3), D(4)$

Explanation

$NaOH$ is caustic soda, used in soap industries for saponification

$Na_2S_2O_3$ (Sodium thiosulphate) is used as antichlor. Antichlor is used in bleaching of chlorine compounds.It is chemical that reacts with, any free chlorine or hypochlorite and neutralizes.

$NaCN$ (Sodium Cyanide) is used in soaps as a germicide.it kill the harmfull microbes.

$Na_2CO_3$ Sodium Carbonate is used in reduction of melting point of silica in the glass industries

Thus Correct option is A

Which of the following does not illustrate the anomalous behaviour of lithium?

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Lithium reacts with nitrogen to form a nitride
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Lithium is the hardest alkali metal
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Lithium reacts with oxygen to form normal oxide only
0%
Lithium carbonate decomposes on heating

The element which exists in liquid state for a wide range of temperature and can be used for measuring high temperature is

0%
$B$
0%
$Al$
0%
$Ga$
0%
$In$

Explanation

Galium

$(Ga)$ with unusually low melting point

$(303 \,K)$ can exist in liquid state during summer. Its high boiling point

$(2676 \,K)$ makes it a useful material for measuring high temperature.

The set representing the correct order of ionic radius is:

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$Li^+ > Be^{2+} > Na^{+} > Mg^{2+}$
0%
$Na^+ > Li^+ > Mg^{2+} > Be^{2+}$
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$Li^+ > Na^+ > Mg^{2+ } > Be^{2+}$
0%
$Mg^{2+} > Be^{2+} > Li^+ > Na^+$

Which among the following is least soluble in water?

0%
$NaF$
0%
$LiF$
0%
$KF$
0%
$RbF$

Beryllium and aluminium exhibit many properties that are similar. But the two element differ in:

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Forming covalent halides
0%
Forming polymeric hydrides
0%
Exhibiting maximum covalency in compounds
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Exhibiting amphoteric nature in their oxides

Pick out statement (s) which is (are) not true about the diagonal relationship of

$Li$ and

$Mg$ :

$A.$ Polarising powers of

$Li^{+}$ and

$Mg^{2+}$ ions are almost same.

$B.$ Like

$Li, Mg$ decomposes water very fast.

$C.$

$LiCl$ and

$MgCl_{2}$ are deliquescent.

$D.$ Like

$Li, Mg$ readily reacts with liquid bromine at ordinary temperature.

0%
$A$ and $D$
0%
$B$ and $C$
0%
Only $B$
0%
$B$ and $D$

The correct order if mobility of alkali metal ions in aqueous solution is:

0%
$K^{+}>Rb^{+}>Na^{+}>Li^{+}$
0%
$Rb^{+}>K^{+}>Na^{+}>Li^{+}$
0%
$Li^{+}>Na^{+}>K^{+}>Rb^{+}$
0%
$Na^{+}>K^{+}>Rb^{+}>Li^{+}$

Alkaline earth metals are characterised by:

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$ns^2$ electronic configuration
0%
electropositive nature
0%
reducing nature
0%
found in nature

Consider the cations,

$Li^+, Be^{2+}, K^+$ and

$Al^{3+}$ . The largest and the smallest ions from this list are respectively:

0%
$K^+$ and $Li^+$
0%
$Al^{3+}$ and $Be^{2+}$
0%
$Mg^{2+}$ and $Li^+$
0%
$K^+$ and $Be^{2+}$

A metal

$M$ readily forms water soluble sulphate and water insoluble hydroxide,

$M(OH)_2$ . Its oxide

$MO$ is amphoteric, hard and having high melting point. The alkaline earth metal is :

0%
$Mg$
0%
$Ca$
0%
$Be$
0%
$Ba$

Explanation

Beryllium forms Beryllium sulfate $(BeSO_4)$ which is water-soluble.
Beryllium forms Beryllium hydroxide $(Be(OH)_2)$ which is water-insoluble.
Beryllium forms Beryllium oxide $(BeO)$ which is amphoteric, hard, and having high melting point.

1962766_1733886_ans_582cd32b0ee94fab8bc7093f349d5c49.jpg

The ion having maximum value of hydration energy is:

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$Li^+$
0%
$Na^+$
0%
$K^+$
0%
$Cs^+$

Which of the following statement(s) is/are INCORRECT ?

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Generally the radius trend and the ionization energy trend across a period are opposite.
0%
Metallic and covalent radii of potassium are 2.3 $A ^0$ and 2.03 $A^0$ respectively.
0%
Amongst $Li^{-}$ , $B^{-}$ and $C^{-}$ , $Li^{-}$ is least stable ion
0%
Atomic and ionic radii of Niobium and Tantalum are almost same.

Explanation

(A) Across the period ,size decreases as electrons are added in the same shell and nuclear charge increases by one unit for addition of each successive element.

In contrary ,the ionization energy increases as size of atom decreases and nuclear charge increases.

(B)

$r_{metalic}> r_{covalent}$ (covalent bond formation involves the overlapping of orbitals.

(C)

$^{_{3}^\textrm{}}Li^{-}$ -

$1s^{2}2s^{2}$ completely filled stable configuration ,so more stable.

$_{4}^\textrm{}Be^{-}$ -

$1s^{2}2s^{2}2p^{1}$

$_{5}\textrm{}B^{-}$ -

$1s^{2}2s^{2}2p^{2}$

$_{6}^\textrm{}C^{-}$ -

$1s^{2}2s^{2}2p^{3}$ half filled stable configuration ,so more stable.

Option C is correct.

Which of the following statements about alkaline earth metals are correct?

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Hydration energy of $Sr^{2+}$ is greater then that of $Be^{2+}$
0%
$CaCO_3$ decomposes at a higher temperature than $BaCO_3$
0%
$Ba(OH)_2$ is stronger base than $Mg(OH)_2$
0%
$SrSO_4$ is less soluble in water than $CaSO_4$

Which of the following statement (s) is/are true for the solutions of alkali metals and alkaline earth metals in ammonia

$(\ell)?$

0%
Concentrated solutions of alkali metals in ammonia are copper - bronzed coloured and have a metallic lusture.
0%
Dilute solutions of alkaline earth metals are deep bule-black in coldur due to the spectrum from the solvated electron.
0%
Concentrated solutions of the alkaline earth metals in ammonia are bronze coloured.
0%
Evaporation of the ammonia from solutions of alkali metals yields the metal, but with alkaline earth metals evaporation of ammonia gives hexammoniates of the metals.

Explanation

(A) Due to the formation of metal ion dusters.

(B)

$M + (x + y) NH_3 \rightarrow M^+ (NH_3)_x + e^- (NH_3)_y$

(D)

$M (NH_3)_6 \rightarrow$ true statement.

All the statements are true

Which of the following statements is true?

0%
$BeO$ and $Be\left(OH\right)_{2}$ both are purely basic in nature.
0%
$Be$ can expand its covalency to six.
0%
$Be$ largely forms covalent compounds which get easily hydrolysed.
0%
$Be$ combines with hydrogen upon heating to form $BeH_{2}$

Explanation

(A)

$BeO$ and

$Be\left(OH\right)_{2}$ are amphoteric in nature.

(B)

$Be$ cannot expand its covalency greater than four as it does not have vacant d-orbitaks.

(D) Do not combine directly with

${H}_{2}$ on heating to form hydride.

Method used is:

$2BeCl_{2}+LiAlH_{4}\longrightarrow2BeH_{2}+LiCl+AlCl_{3}$

$Na$ is heated in presence of air, it forms

0%
$Na_2CO_3$
0%
$Na_2O_2$
0%
$Na_2O$
0%
Both $(B)$ and $(C)$

Explanation

When Na is heated in the presence of air or oxygen, Na burns to form sodium oxide and sodium peroxide.

$6Na+2O_2\to 2Na_2O+Na_2O_2$

Sodium metal cannot be stored under

0%
benzene
0%
kerosene
0%
alcohol
0%
toluene

Explanation

Sodium metal cannot be stored under alcohol because it reacts with alcohol to form sodium alkoxide and hydrogen gas.

$2C_2H_5OH +2Na \rightarrow 2C_2H_5ONa+H_2$

Magnesium is a non-combustible metal.

0%
True
0%
False

Point out of the incorrect statements regarding

$Be$ (Group

$IIA$ )

0%
It forms an ionic carbide
0%
Its carbonates decomposes on heating
0%
Its halides are covalent
0%
It is easily attacked by water

Explanation

$Be$ does not react easily with normal water. Beryllium reacts with water to produce oxide beryllium, beryllium hydroxide and hydrogen. The reaction takes place in a boiling solution.

$2Be + 3H_2O \to BeO + Be(OH)_2 + 2H_2$

Write 'true ' or 'false' for the following statements :
Sodium can be cut with a knife.

0%
True
0%
False

Which of the following has maximum solubility in water?

0%
NaCl
0%
KCl
0%
RbCl
0%
LiCl

Explanation

As we go down group

$\mathrm{I}$ , solobulity of chlorides increases.

So, RbCl has the maximum solubility in water.

Hence, Option "C" is the correct answer.

The atomic radii of alkali metals

$(M)$ lie in the order

$Li < Na < K < Rb$ but the radii of

$M^{+}$ ions in aqueous solution lie in the reverse order

$Li^{+} > Na^{+} > K^{+} > Rb^{+}$ . What is the reason for this reverse order (on going from

$Li$ to

$Rb$ )?

0%
Gradual increase in ionisation energy
0%
Increasing weakness of the metallic bond
0%
Increasing electropostive character
0%
Decreasing degree of hydration

Which of the following shows highest oxidation state of

$+7$ ?

0%
$Co$
0%
$Cr$
0%
$Mn$
0%
$v$

Beryllium differs from the rest of the alkaline earth metals on account of its small size, and high electronegativity as compared to other alkaline earth metals. However, it shows a diagonal relationship with aluminium of the next period. Due to the high polarising power of

$Be^{2+}$ and

$Al^{3+}$ their compounds develop a covalent nature.

Which of the following is not a similarity of beryllium with aluminium ?

0%
It becomes passive when treated with conc. $HNO_3$ .
0%
It forms polymeric covalent hydrides.
0%
Carbonates of Be is extremely stable.
0%
Salts of Be do not impart colour to the flame.

Paramagntism is common in:

0%
s-block elements
0%
p-block elements
0%
f-block elements
0%
d-block elements

The compounds of alkaline earth metals have the following magnetic nature are:

0%
Diamagnetic
0%
Paramagnetic
0%
Ferromagnetic
0%
Antiferromagnetic

Property of alkaline earth metals which increases with their atomic number is:

0%
Ionization energy
0%
solubility of their hydroxides
0%
solubility if their sulphates
0%
electronegativity

Which of the following pairs do not have the same nature?

0%
$B(OH)_{3}, H_{3}PO_{3}$
0%
$Be(OH)_{2}, Al(OH)_{3}$
0%
$B(OH)_{3}, Al(OH)_{3}$
0%
$Mg(OH)_{2}, NaOH$

Explanation

Option A: Both are acidic in nature.

$B(OH)_{3}$ is orthoboric acid.

$H_{3}PO_{3}$ is phosphorous acid.

Option B: Both are amphoteric hydroxides.

Option C:

$B(OH)_{3}$ is acidic and

$Al(OH)_{3}$ is amphoteric.

Option D: Both are basic hydroxides.

Hence, option (C) is the correct answer.

CBSE Questions for Class 11 Medical Chemistry The S-Block Elements Quiz 13 - MCQExams.com

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Practice Class 11 Medical Chemistry Quiz Questions and Answers

CBSE Questions for Class 11 Medical Chemistry The S-Block Elements Quiz 13 - MCQExams.com

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Practice Class 11 Medical Chemistry Quiz Questions and Answers

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