MCQ Questions for Class 11 Medical Chemistry The S-Block Elements Quiz 2

Which element has valency equal to its group number?

0%
Sodium
0%
aluminium
0%
oxygen
0%
carbon

Explanation

Sodium having atomic number 11, its electronic configuration is

$(Na)11-1s_2 2s_2 2p_6 3s_1$

therefore sodium contains one valence electron and having group no. first.

The metal used in solar cells is:

0%
Na
0%
Li
0%
Cs
0%
Mg

Explanation

Among the given metals, Caesium (

$Cs$ ) has the lowest ionization enthalpy. Hence it loses electrons readily. Therefore, caesium is used in solar cells.

The lightest metal among the following is:

0%
Cs
0%
Be
0%
Na
0%
Li

Explanation

$Li$ is the lightest metal because it is placed in first group of periodic table i.e. in alkali metal group and it has the lowest atomic number.

Li shows diagonal relationship with:

0%
Mg
0%
Be
0%
Al
0%
B

Explanation

Hint: Elements that show similar chemical and physical properties.

Correct answer: Option

$A$

Explanation of correct option:

When the first element of a group shows similarities in properties with the second element of the next group. This is called, 'diagonal relationship between these two elements.

Both

$Li$ and

$Mg$ shows a diagonal relationship with each other because these elements present diagonally in the periodic table and have the following similarities:

Both have similarities in electronegativities.
Both are hard metals.
$LiOH$ and $Mg(OH)_{2}$ are weak bases.

Explanation of incorrect options:

All other elements are not placed diagonally in the periodic table and do not show any similarities in their chemical or physical properties with

$Li$ . Hence, these are not in a diagonal relationship.

The least electropositive alkali metal is:

0%
Sodium
0%
Lithium
0%
Potassium
0%
Caesium

The softness of group

$IA$ metals increases down the group because:

0%
the metallic bond strength decreases with increase in atomic size
0%
ionisation potential decreases from $Li$ to $Cs$
0%
electronegativity increases from $Li$ to $Cs$
0%
atomic size decreases from $Li$ to $Cs$

STATEMENT-1 :

$Be$ and

$Al$ form amphoteric oxides.
STATEMENT-2 :

$Be$ and

$Al$ are metalloids.

0%
STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is a correct explanation for STATEMENT-1
0%
STATEMENT-1 is True, STATEMENT-2 is True; STATEMENT-2 is NOT a correct explanation for STATEMENT-1
0%
STATEMENT-1 is True, STATEMENT-2 is False
0%
STATEMENT-1 is False, STATEMENT-2 is True

Explanation

$Be$ and $Al$ form the amphoteric oxides, $BeO$ and $Al_2O_3$ respectively. These oxides can behave both as base as well as acids.

Aluminium $(Al)$ is a lightweight silvery-white metal and beryllium is also a steel-gray metal which is quite brittle at room temperature and resembles some of the properties of aluminium.

Hence, STATEMENT-1 is true and STATEMENT-2 is false.

Therefore, Option (C) is correct.

Which of the following undergoes decomposition on heating?

0%
$Li_{2}CO_{3}$
0%
$K_{2}CO_{3}$
0%
$Na_{2}CO_{3}$
0%
$Rb_{2}CO_{3}$

Explanation

Alkali metals are electro-positive in nature. They form stable carbonates. On moving down the group, the thermal stability of the carbonates increases with an increase in the electro-positive nature. Lithium is an exception. Lithium carbonate (

$Li_2CO_3$ ) easily decomposes on heating. It is because of the high charge density of

$Li^+$ ion.

Which one of the following has a polarizing power close to that of Mg?

0%
Li
0%
Na
0%
K
0%
Rb

Match compounds given in List 1 with their use in List 2

List 1	List 2
A. Liquid sodium metal	breathing apparatus submarine
B. Potassium	explosive stearate
C. Potassium nitrate	coolant in the nuclear reactor
D. Potassium superoxide	soft soap

0%
A-1; B-2; C-3; D-4
0%
A-3; B-4; C-2; D-1
0%
A-1; B-4; C-2; D-3
0%
A-4; B-3; C-2; D-1

Explanation

Liquid sodium metal is used as a coolant (heat-transfer medium) in a nuclear reactor.

Potassium is used in the preparation of potassium hydroxide which is used in the manufacture of soft soap.

Potassium nitrate is used in ceramics, colour TV tubes, fluorescent light tubes and explosive stearate.

Potassium superoxide is used in breathing apparatus, submarine and space capsules.

$\displaystyle KO_2$ reacts directly with

$CO$ and

$\displaystyle CO_2$ producing

$\displaystyle O_2$ as follows:

$\displaystyle 2KO_2 + CO \rightarrow K_2CO_3 + O_2$

$4KO_2 + 2CO_2 \rightarrow 2K_2CO_3 + 3 O_2$

$4KO_2 + 4CO_2 +2H_2O \rightarrow 4KHCO_3 +3O_2$

Which of the following property of alkali metals increases with increase in atomic number?

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

Metals having

$ns^{1}$ as the valence electronicconfiguration :

0%
act as strong oxidizing reagent
0%
are highly electronegative
0%
are highly electropostive
0%
have a first ionization potential of more than 10 eV/atom

Explanation

Alkali metals have valence electronic configuration

$ns^1$ . They are highly electropositive elements with low ionization energies. They act as strong reducing agents.

What is the correct increasing order of solubility of the following salt?

$NaHCO_3,\ KHCO_3,\ Mg(HCO_3)_2,\ Ca(HCO_3)_2$

0%
$KHCO_3<Mg(HCO_3)_2<Ca(HCO_3)_2<NaHCO_3$
0%
$Mg(HCO_3)_2<Ca(HCO_3)_2<NaHCO_3<KHCO_3$
0%
$NaHCO_3<KHCO_3<Mg(HCO_3)_2<Ca(HCO_3)_2$
0%
$Ca(HCO_3)_2<NaHCO_3<KHCO_3<Mg(HCO_3)_2$

Explanation

In the give metal bicarbonates, the anion (bicarbonate ion) is the same. Hence the solubility will depend on the size of cation. The size of

$Na^+$ ion is smaller than that of

$K^+$ ion. Hence sodium bicarbonate has high lattice energy and lower solubility than potassium bicarbonate. Similarly, the size of

$Mg^+$ ion is smaller than that of

$Ca^+$ ion. Hence magnesium bicarbonate has high lattice energy and lower solubility than calcium bicarbonate.

Hence, the correct option is

$(C)$

$Li,\ Na$ and

$K$ burn in excess of air to form:

0%
$Li_{2}O,\ Na_{2}O$ and $K_{2}O$
0%
$Li_{2}O,\ Na_{2}O_{2}$ and $K_{2}O$
0%
$Li_{2}O,\ Na_{2}O_{2}$ and $KO_{2}$
0%
$Li_{2}O,\ NaO_{2}$ and $K_{2}O_{2}$

Explanation

$Li,\ Na$ and

$K$ burn in excess of air to form lithium monoxide (

$Li_2O$ ), sodium peroxide (

$Na_2O_2$ ) and potassium superoxide (

$KO_2$ ) respectively.

Hence, option C is the correct answer.

Which of the following can form a super oxide very easily?

0%
Sodium
0%
Potassium
0%
Caesium
0%
Lithium

Sodium burns in excess air to give mainly:

0%
$Na_{2}O$
0%
$NaO_{2}$
0%
$Na_{2}O_{2}$
0%
$NaH$

Explanation

Sodium burns in excess air to form peroxide (

$Na_2O_2$ ).

$2Na\ + O_2\ \xrightarrow { } Na_{ 2 }O_{ 2 }$

When Na and Li are burnt in dry air, we get :

0%
$NaOH$ , $Na_{2}O$ , $Li_{2}O$
0%
$Na_{2}O$ , $Li_{2}O$
0%
$Na_{2}O$ , $Li_{2}O$ , $Li_{3}N$ , $NH_{3}$
0%
$Na_{2}O_{2}$ , $Li_{3}N$ , $Li_{2}O$

Explanation

Lithium burns in air to form lithium monoxide (

$Li_2O$ ) and lithium nitride (

$Li_3N$ ). Sodium burns in air to form sodium peroxide (

$Na_2O_2$ ).

Pick out the false statement :

0%
the electropostive character of alkali metals decreases with increases in atomic number
0%
lithium is a hard metal and cannot be cut with a knife
0%
Alkali metals are strong reducing agents
0%
the electro-negativities of all alkali metals remain the same.

The sulphate of which metal given below has the highest solubility in water?

0%
$Ca$
0%
$Ba$
0%
$Sr$
0%
$Mg$

Explanation

On moving down the group of alkaline earth metals, the solubility of metal sulphates decreases. Also, the ionic size increases and hydration energy of metal ion decreases. Hence, magnesium sulphate(

$MgSO_4$ ) has lowest solubility.

Which of the following statement is correct?

0%
Lithium carbonate is soluble in water.
0%
Carbonates of Ca and Ba are soluble in water.
0%
Carbonates of $Na^{+},\ K^{+}$ and $NH_4^{+}$ are soluble in water.
0%
All the above.

Alkali metal when exposed to air tarnish quickly due to the ________.

0%
formation of their hydroxides
0%
formation of their carbonates
0%
formation of their oxides
0%
all the above

The ion helpful for controlling heart beating and muscle contraction is:

0%
$Mg^{2+}$
0%
$Na^{+}$
0%
$K^{+}$
0%
$Ca^{2+}$

Explanation

${ Ca }^{ 2+ }$ is the ion helpful for controlling heart beat and muscle contraction.

The enamel on teeth contains:

0%
fluorapatite
0%
chlorapatite
0%
apatite
0%
calcium monohydrogen phosphate

Explanation

The enamel on teeth contains fluorapatite which is a phosphate mineral and contains calcium. Its formula is

$Ca_5(PO_4)_3F$ .

Chlorophyll, the green component of plants contains:

0%
$Ca^{2+}$
0%
$Be^{2+}$
0%
$Mg^{2+}$
0%
$Ba^{2+}$

Explanation

In plants,

$Mg^{2+}$ is present in chlorophyll which is a green pigment useful for photosynthesis. It absorbs sunlight.

The alkaline earth metal whose carbonate has no natural occurrence is:

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

A burning strip of

$Mg$ is introduced into a jar containing a gas. After some time, the walls of the container are coated with carbon. The gas in the container is :

0%
$O_{2}$
0%
$N_{2}$
0%
$CO_{2}$
0%
$H_{2}O$

Explanation

Magnesium burns in carbon dioxide to form magnesium oxide and carbon.

$2Mg+CO_2 \rightarrow 2MgO+C$

Which of the following metals cannot give flame
tests?

0%
Be
0%
Na
0%
K
0%
Ca

Which of the following is the strongest reducing agent?

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

Which of the following salt gives a crimson red colour in flame test?

0%
$BaCl_{2}$
0%
$CaCl_{2}$
0%
$BeCl_{2}$
0%
$SrCl_{2}$

Explanation

Strontium chloride(

$SrCl_2$ ) gives crimson red colour in the flame test. It is due to the excitation of electrons by the thermal energy, which is then followed by de-excitation of electron to ground state along with liberation of light in the visible range.

The metal which gives brick red colour in flame test is :

0%
barium
0%
calcium
0%
strontium
0%
radium

Which of the following statement is correct?
I) Atomic radius of Na is greater than that of Mg.
II) Metallic bond in Mg is stronger than the metallic bond in Na.
III) Melting and boiling points of Mg are greater than that of Ca.
IV) Mg and Ca are most abundant elements among the alkaline earth metals.

0%
III, IV
0%
I, II, IV
0%
II, IV
0%
I, IV

Explanation

The nuclear charge of sodium is lower than the nuclear charge of magnesium. Hence, the atomic radius of sodium is greater than that of magnesium.
Due to greater nuclear charge of

$Mg$ than that of

$Na$ , the attraction of nucleus for outermost electron is stronger for

$Mg$ than for

$Na$ . Hence, the metallic bond in

$Mg$ is stronger than that of

$Na$ .
Magnesium has lower melting and boiling points than that of

$Ca$ . This is due to higher effective nuclear charge on

$Ca$ than

$Mg$ which leads to stronger bonds.
Among the alkaline earth metals,

$Mg$ and

$Ca$ have highest abundance.

The thermal stability of

$BaCO_{3}, CaCO_{3}$ and

$MgCO_{3}$ is:

0%
$CaCO_{3} > MgCO_{3} > BaCO_{3}$
0%
$MgCO_{3}> CaCO_{3} > BaCO_{3}$
0%
$BaCO_{3} > MgCO_{3} > CaCO_{3}$
0%
$BaCO_{3} > CaCO_{3} > MgCO_{3}$

Explanation

On moving down the group of alkaline earth metals, the thermal stability of carbonates increases. As the atomic number increases, the difference in the stability of metal cation and the oxide anion increases. Thus, the stability of the decomposition product metal oxide decreases, as close packing is not possible. Hence, the stability of the carbonate increases. Thus, among the given carbonates, the order of thermal stability is

$BaCO_3>CaCO_3>MgCO_3$ .

Sulphate of an alkaline earth metal which crystalizes without water of hydration is?

0%
$Be^{2+}$
0%
$Mg^{2+}$
0%
$Ca^{2+}$
0%
$Sr^{2+}$

Which of the following does not form peroxides?

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

Explanation

Beryllium does not form peroxides due to its very small size and high polarizing power of

$Be^{2+}$ cation. However,

$Ba,\ Ca$ and

$Mg$ form peroxides.

Assertion(A) : Beryllium and magnesium do not impart characteristic colour in flame.
Reasoning(R) : Both Beryllium and magnesium have high I.E.

0%
Both Assertion and Reason are true and Reason is the correct explanation of Assertion
0%
Both Assertion and Reason are true but Reason is not a correct explanation of Assertion
0%
Assertion is true but Reason is false
0%
Both Assertion and Reason are false

A substance X, which is an oxide of a group 2 element, is used intensively in the cement industry. This element is present in bones also. On treatment with water, it forms a solution which turns red litmus blue. Identify X :

0%
Calcium oxide
0%
Magnesium oxide
0%
Beryllium oxide
0%
Barium oxide

Explanation

Substance X is calcium oxide

$(CaO)$ , also known as quicklime. It is an important ingredient in the processing of cement. Calcium oxide reacts with water to form calcium hydroxide

$Ca(OH)_{2}$ which is a base and therefore, turns red litmus blue. The equation can be written as:

$2CaO(s) + H_{2}O(l) \rightarrow Ca(OH)_{2}(aq)$

Beryllium shows diagonal relationship with:

0%
B
0%
Mg
0%
Al
0%
Ne

Explanation

$\bf {Hint}:$ Elements that show similar chemical and physical properties.

$\bf {Correct \ answer:}$ Option

$C$

$\bf {Explanation \ of \ correct \ option:}$

When the first element of a group shows similarities in properties with the second element of the next diagonal group. This is called, 'diagonal relationship between these two elements.

Both

$Be$ and

$Al$ shows a diagonal relationship with each other because these elements present diagonally in the periodic table and have the following similarities:

Both halides like $BeCl_{2}$ and $AlCl_{3}$ act as Lewis acids.
$Al$ has electronegativity about $1.61$ and $B$ has $1.58$ which are approx same.
Both elements form covalent compounds.

$\bf {Explanation \ of \ incorrect \ options:}$

Both remaining pairs are not placed diagonally in the periodic table and do not show any similarities in their chemical or physical properties. Hence, these are not in a diagonal relationship.

Select the correct order of density.

0%
Na > K
0%
Na < K
0%
Mg > Ca
0%
Mg < Ca

Explanation

The trend of density amongst alkali metals:

$Li<K<Na<Rb<Cs$

The trend of density amongst alkaline earth metals:

$Ca<Mg<Be<Sr<Ba<Ra$

Hence the correct choices are

$Na>K$ and

$Mg>Ca$

Which of the following statements is/are not true about the diagonal relationship of

$Be$ and

$Al$ ?
a) Both react with

$NaOH$ to liberate hydrogen.
b) Their oxides are basic.
c) They become passive by concentrated

$HNO_{3}$ .
d) Their carbides give acetylene on treatment with water.

0%
Only $a$
0%
$b$ and $c$
0%
$a$ and $d$
0%
$b$ and $d$

Explanation

The oxides of beryllium and aluminum are amphoteric in nature. Hence, statement

$b$ is not true. On treatment with water, the carbides of

$Be$ and

$Al$ give methane. Hence, statement

$d$ is incorrect.
Option D is correct.

Metal

${\text{M + air}}\xrightarrow{\Delta }{\text{A}}\xrightarrow{{{{\text{H}}_{\text{2}}}{\text{O}}}}B\xrightarrow{{{\text{HCl}}}}{\text{White fumes}}$ ; Metal

$M$ can be:

0%
$\rm{ Li,\, Mg }$
0%
$\rm{ Na,\, K }$ or $\rm{Mg}$
0%
$\rm{ Li,\, Al }$ or $\rm{ K }$
0%
$\rm{ Li,\, Na }$ or $\rm{ K }$

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

0%
$CaSO_{4}$
0%
$BeSO_{4}$
0%
$BaSO_{4}$
0%
$SrSO_{4}$

Explanation

Hydration energy decreases down the group, whereas lattice energy remains almost constant. Thus, hydration enthalpy is higher than the lattice enthalpy in case of

$BeSO_4$ .

So, the correct answer is

$B.$

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

0%
${Be_{2}}^{+}$
0%
$Be_{2}$
0%
$B_{2}$
0%
L $i_{2}$

Explanation

$Be_{2}$ does not exist under normal condition. Beryllium has four electrons , so electronic configuration of

$Be_{2}$ having 8 electrons will be

$\sigma 1s^{2} \sigma^{*}1s^{2} \sigma 2s^{2} \sigma^{*} 2s^{2}$ and the bond order is

$\cfrac{N_{a} - N_{b}}{2} = 0$

Since

$Be_{2}$ is having bond order 0 , no bond is formed between the two atoms. Hence

$Be_{2}$ is unstable

Mg is present in

0%
Chlorophyl
0%
Haemoglobin
0%
Vitamin-12
0%
Vitamin-B

Alkaline earth metal(s) which does (do) not
impart colour to the flame is (are):

0%
Be
0%
Mg
0%
Ca
0%
Sr

Explanation

Beryllium(

$Be$ ) and magnesium(

$Mg$ ) cannot give flame test. They have small size. They strongly binds their electrons. Thus they have high ionization enthalpies. The thermal energy of flame is not sufficient to excites their electrons.

Sodium and potassium react with water much more vigorously than lithium because:

0%
sodium and potassium have high values of hydration energy as compared to that of lithium
0%
sodium and potassium have higher melting point than that of lithium
0%
sodium and potassium have lower melting point than that of lithium
0%
sodium and potassium have lower hydration energy than that of lithium

Explanation

When sodium and potassium react with water, the heat evolved causes them to melt, giving a larger area of contact with water, lithium on the other hand, does not melt under these condition and thus reacts more slowly.

Li Na K

180 98 64 Melting point

$(^oC)$

The colour of transition metal compound is due to :

0%
complete $n-subshell$ .
0%
small size metal ion.
0%
incomplete $(n-1)d-subshell$ .
0%
none of these.

Alkaline earth metal nitrates on heating decompose to give:

0%
$M(NO_2)_2$ and $O_2$ only
0%
$MO, N_2$ and $O_2$
0%
$MO, NO_2$ and $O_2$
0%
$MO$ and $NO_2$ only

Explanation

Alkaline earth metal nitrates on heating decompose to give metal oxide, nitrogen dioxide and oxygen gas. These are white solid and brown nitrogen dioxide and oxygen gas is given off when heated.

$2M(NO_3)_2 \rightarrow 2MO + 4NO_2 + O_2$

Consider the following statements and arrange in the order of true/false as given in the codes.

$S_1$ : Sodium amalgam reacts with hot water and produces sodium hydroxide and hydrogen gas.

$S_2$ : Sodium is more reactive than potassium.

$S_3$ : Alkaline earth metals dissolve in liquid ammonia to give deep blue-black solutions which are conducting.

$S_4$ : Alkaline earth metal salts have more number of water molecules as compared to those of alkali metal salts.

0%
TTFF
0%
TFTT
0%
FTTF
0%
TFFT

Property of all the alkaline earth metals that increases with their atomic number is:

0%
solubility of their carbonates
0%
thermal stability of their sulphates
0%
ionisation energy
0%
electronegativity

The energy of an electron in a particular orbit of single electron species of beryllium is the same as the energy of an electron in the ground state of a hydrogen atom. Identify the orbit of beryllium.

0%
1
0%
2
0%
3
0%
4

Explanation

Energy of an electron in

$Be^{+3}$ ion

$\displaystyle = \frac{-13.6}{n^2} \times 4^2 ev$
Energy of electron in ground state hydrogen atom

$=-13.6 ev$

$\therefore \displaystyle \frac{-13.6}{n^2} \times 4^2 =-13.6$

$\Rightarrow n^2 = 4^2$

$\therefore \displaystyle \frac{-13.6}{4^2} \times 4^2 =-13.6$

we get -13.6 on both sides

$\Rightarrow n = 4$

CBSE Questions for Class 11 Medical Chemistry The S-Block Elements Quiz 2 - 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 2 - MCQExams.com

0:0:1

Practice Class 11 Medical Chemistry Quiz Questions and Answers

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