The s-Block Elements Test 36

Result

The s-Block Elements Test 36

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

When sodium is heated in moist air, the ultimate product obtained is:

A
$$\displaystyle Na_{2}O $$

B
$$NaOH$$

C
$$\displaystyle Na_{2}CO_{3} $$

D
$$\displaystyle Na_{2}O_{2} $$

Solution

When sodium is heated with moist air, the ultimate product obtained is $$\displaystyle Na_2CO_3 $$.
In moist air, a layer of sodium oxide, hydroxide and carbonate is formed on its surface due to which, it loses its lustre.
The complete reaction sequence is as follows:
$$\displaystyle 4Na + O_2 \rightarrow 2Na_2O \xrightarrow {2H_2O} 4NaOH \xrightarrow {2CO_2} 2 Na_2CO_3 + 2H_2O $$
Question 2
1 / -0

The re-activity of Ca, Sr, Mg and Ba with water follow the order :

A
$$Sr > Ba > Mg > Ca$$

B
$$Ba > Sr > Ca > Mg$$

C
$$Ca > Mg > Ba > Sr$$

D
$$Sr > Ca > Mg > Ba$$

Solution

The re-activity of $$Ca,\ Sr, \ Mg$$ and $$Ba$$ with water follow the order :

$$\displaystyle Ba > Sr > Ca > Mg$$

On moving down the group of alkaline earth metals, the reactivity with water increases.

$$Be$$ does not react even with boiling water. $$Mg$$ reacts with boiling water. $$Ca,\ Sr,\ Ba$$ react vigorously even with cold water.

Hence option B is correct.
Question 3
1 / -0

Alkali metals readily react with oxyacids forming corresponding salts like $${ M }_{ 2 }{ CO }_{ 3 }$$, $${ M }H{ CO }_{ 3 }$$, $${ M }N{ O }_{ 3 }$$, $${ M }_{ 2 }{ SO }_{ 4 }$$, etc. with evolution of hydrogen. They also dissolve in liquid $${ NH }_{ 3 }$$ but without the evolution of hydrogen. The color of its dilute solution is blue but when it is heated and concentrated then its color becomes bronze.

Which of the following statement about the sulphate of alkali metal is correct :

A
except $${ Li }_{ 2 }{ SO }_{ 4 }$$ all sulphate of other alkali metals are soluble in water.

B
all sulphates of alkali metals except lithium sulphate forms alum.

C
the sulphates of alkali metals cannot be hydrolysed.

D
all of these.

Solution

Except $${ Li }_{ 2 }{ SO }_{ 4 }$$ all sulphate of other alkali metals are soluble in water and forms alum. Thus, they form double salts with the sulphates of trivalent metals like $$Al, Fe, Cr$$ etc. The sulphates of alkali metals cannot be hydrolysed as they are salts of a strong acid and strong base.
Question 4
1 / -0

Select the correct order of ionic conductance of the following cations in an aqueous solution.

A
$${ Li }^{ + }<{ Na }^{ + }<{ K }^{ + }<{ Rb }^{ + }$$

B
$${ Li }^{ + }>{ Na }^{ + }>{ K }^{ + }>{ Rb }^{ + }$$

C
$${ Li }^{ + }<{ Na }^{ + }>{ K }^{ + }>{ Rb }^{ + }$$

D
$${ Li }^{ + }={ Na }^{ + }<{ K }^{ + }<{ Rb }^{ + }$$

Solution

Smaller is the size of cation, greater will be the mobility and hence, the conductivity. The size of the cation increases as we move from $$Li^{+}$$ to $$Rb^{+}$$. Hence, the conductivity should decrease. However, in aqueous solution, due to very small size of $$Li^+$$, it is strongly hydrated and hence, its effective hydrated size is greater than that of $$Rb^+$$.
So, the correct order of increasing ionic conductance is as follows:
$${ Li }^{ + }<{ Na }^{ + }<{ K }^{ + }<{ Rb }^{ + }$$
Hence, option A is correct.
Question 5
1 / -0

Which of the following has the maximum coordinate number not more than 4?

A
Beryllium

B
Calcium

C
Barium

D
Radium

Solution

Option $$(A)$$ is correct.
Beryllium has the maximum coordinate number not more than 4 as it has four orbitals in the valence shell. The other members of this group has coordination number 6 by making use of $$d$$- orbitals.
Question 6
1 / -0

Among the following hydroxides, the one which has the lowest value of $$K_{sp}$$at ordinary temperature is:

A
$$Be(OH)_2$$

B
$$Mg(OH)_2$$

C
$$Ca(OH)_2$$

D
$$Ba(OH)_2$$

Solution

Option $$(A)$$ is correct.
$$Be(OH)_2$$ has the lowest value of $$K_{sp}$$ at ordinary temperature because $$Be^{2+}$$ ion is smaller than the other metal ions in the group, which results in a tighter bond with the $$0H^-$$ ions, thus much lower solubility.
The solubility of a hydroxide of group 2 elements increases down the group because as you go down the group size of metal increases thereby increasing the bond length and decreasing bond energy.
Question 7
1 / -0

Which of the following does not decompose water?

A
$$Be$$

B
$$Mg$$

C
$$Ca$$

D
$$Sr$$

Solution

Option $$(A)$$ is correct.
$$Be$$ does not decompose water due to its small size and high ionisation energy but it will react with the oxygen of $$H_2O$$.
Question 8
1 / -0

A metal $$M$$ forms water-soluble sulphate $$MSO_4$$, water-insoluble hydroxide$$M(OH)_2$$ and oxide $$MO$$ which becomes inert on heating. The hydroxide is soluble in $$NaOH$$. Then $$M$$ is:

A
$$Be$$

B
$$Mg$$

C
Cannot be determine as data is incomplete

D
$$Sr$$

Solution

Option $$(A)$$ is correct.
$$Be$$ forms water soluble $$BeSO_4$$, water insoluble $$Be(OH)_2$$ and $$BeO$$.$$Be(OH)_2$$ is insoluble in $$NaOH$$ giving sodium beryllate,$$Na_2BeO_2$$.
On moving down, water solubility of alkaline earth metals decreases.Oxides and hydroxides of alkaline earth metal are basic except $$Be$$ which is amphoteric.Hence, the metal is $$Be$$.
Question 9
1 / -0

Which of the following alkaline earth metal does not impart characteristic colour to flame?

A
$$Ca$$

B
$$Sr$$

C
$$Ba$$

D
$$Be$$

Solution

Option $$(D)$$ is correct.
$$Be$$ does not impart characteristic colour to flame because its atoms are comparatively smaller and the valance electrons are strongly attached to the nucleus. Therefore its ionisation energies is high and needs large amount of energy for the excitation of their valence electrons to higher energy level which is usually not available in the Bunsen flame. So beryllium do not impart any colour to the flame.
$$Ca, Sr$$ and $$Ba$$ impart brick red, blood red and apple green colours respectively to the flame.
Question 10
1 / -0

Which of the following alkaline earth metal indirectly form a polymeric hydride with three centre bond?

A
$$Mg$$

B
$$Be$$

C
Both $$A$$ and $$B$$

D
none of these

Solution

Option $$(B)$$ is correct.
$$Be$$ indirectly form a polymeric hydride with three centre bond.
$$BeH_2$$ is covalent and has polymeric structure involving multicentre bonds (three-centre two-electron bond).Each beryllium atom is bonded to two hydrogen atoms and each hydrogen atom to two beryllium atoms. Now, beryllium has only two valence electrons and hydrogen only one, it is apparent that there are not sufficient electrons to form so many electron pair bonds. The monomeric $$BeH_2$$, if formed with normal bonds, would have only four electrons in the valence shell of the beryllium atom and would be electron deficient and unstable. It polymerizes to remedy the electron deficiency. The bonds formed cannot be explained by the classical theories of bonding. They are “banana-shaped” molecular orbitals holding three atoms $$Be -- H -- Be$$ together and are called 3 centred – 2 electrons ($$3c – 2e^-$$) bonds.

User

Question Analysis

Correct -
Wrong -
Skipped -

My Perfomance

Score
-
out of -
Rank
-
out of -

Re-Attempt Weekly Quiz Competition

The s-Block Elements Test 36

Result

The s-Block Elements Test 36

Score

-

Rank

-

SHARING IS CARING

Question 1

$$\displaystyle Na_{2}O $$

$$NaOH$$

$$\displaystyle Na_{2}CO_{3} $$

$$\displaystyle Na_{2}O_{2} $$

Solution

Question 2

$$Sr > Ba > Mg > Ca$$

$$Ba > Sr > Ca > Mg$$

$$Ca > Mg > Ba > Sr$$

$$Sr > Ca > Mg > Ba$$

Solution

Question 3

except $${ Li }_{ 2 }{ SO }_{ 4 }$$ all sulphate of other alkali metals are soluble in water.

all sulphates of alkali metals except lithium sulphate forms alum.

the sulphates of alkali metals cannot be hydrolysed.

all of these.

Solution

Question 4

$${ Li }^{ + }<{ Na }^{ + }<{ K }^{ + }<{ Rb }^{ + }$$

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

$${ Li }^{ + }<{ Na }^{ + }>{ K }^{ + }>{ Rb }^{ + }$$

$${ Li }^{ + }={ Na }^{ + }<{ K }^{ + }<{ Rb }^{ + }$$

Solution

Question 5

Beryllium

Calcium

Barium

Radium

Solution

Question 6

$$Be(OH)_2$$

$$Mg(OH)_2$$

$$Ca(OH)_2$$

$$Ba(OH)_2$$

Solution

Question 7

$$Be$$

$$Mg$$

$$Ca$$

$$Sr$$

Solution

Question 8

$$Be$$

$$Mg$$

Cannot be determine as data is incomplete

$$Sr$$

Solution

Question 9

$$Ca$$

$$Sr$$

$$Ba$$

$$Be$$

Solution

Question 10

$$Mg$$

$$Be$$

Both $$A$$ and $$B$$

none of these

Solution

User

Question Analysis

My Perfomance

Score

-

Rank

-

Results Announcement on: coming Monday

Stay Tuned: We’ll update you on your result via email or SMS.