The p-Block Elements Test

Result

The p-Block Elements Test - 62

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Weekly Quiz Competition

Question 1
1 / -0

Select the correct order from the following :

A
$$N_2O < N_2O_3 < NO$$; Acidic character

B
$$MgO > Al_2O_3 > SiO_2$$; Basic character

C
$$Fe^{2+} < Fe^{3+} < Mn^{2+}$$; Ionic radius order

D
$$Sc > La > Y$$; Ionisation energy order

Solution
Question 2
1 / -0

Borax is actually made of two tetrahedral and two triangular units joined together and should be
written as : $$Na_{2}\:[B_{4}O_{5}(OH)_{4}].8H_{2}O$$.
Consider the following statements about borax:
1. Each boron atom has four B-O bonds
2. EAch boron atom has three B-O bonds
3. Two boron atoms have four B-O bonds while other two have three B-O bonds
4. Each boron atom has one-OH groups
Select correct statement(s) -

A
1, 2

B
2, 3

C
3, 4

D
1, 3

Solution

Borax $$Na_{2}\:[B_{4}O_{5}(OH)_{4}].8H_{2}O$$
Question 3
1 / -0

The color imparted by Co(Il) compounds to glass is :

A
deep blue.

B
green.

C
yellow.

D
red.

Solution

Cobalt primarily used as the metal, in the preparation of magnetic, wear-resistant and high-strength alloys.

The color imparted by Co(Il) compounds to glass is deep blue.

Hence, option A is correct.
Question 4
1 / -0

Which one of the following is present in the chain structure of silicates?

A
$$(Si_2O_5^{2-})_n$$

B
$$(SiO_3^{2-})_n$$

C
$$(SiO_4)^{4-}$$

D
$$Si_2O_7^{6-}$$

Solution

Chain silicates: Chain silicates are formed by sharing two oxygen atoms by each tetrahedral. Anions of chain silicate have two general formula:
$$(SiO_3^{2-})_n^{2n-}$$ and $$ (Si_4o_11)_n^{6n-} $$
Question 5
1 / -0

$$ B^{3+} $$ ion can not exist in aqueous solution because of its :

A
strong reducing ability

B
strong oxidizing ability

C
small size and large charge

D
large size and small charge

Solution

On account of higher charge density i.e. charge/size ratio it gets hydrolysed forming $$ H_3BO_3 $$ .
$$ 2B^{3+} + 6H_2O \longrightarrow 2H_3BO_3 + 6H^+ $$
Question 6
1 / -0

Pyrosilicates have _________________ structural unit :

A
$$ Si_3O_9^{6-} $$

B
$$ SiO_4^{4-} $$

C
$$ Si_2O_7^{6-} $$

D
$$ (Si_2O_5^{2-})_n $$

Solution

R.E.F image
$$Si_{2}O_{7}^{6}$$
Question 7
1 / -0

Which of the following anions is present in the simple single chain structure of silicate ?

A
$$ SiO_4^{4-} $$

B
$$ Si_2O_7^{6-} $$

C
$$ (Si_2O_5^{2-})_n $$

D
$$ (SiO_3^{2-})_n $$

Solution
Question 8
1 / -0

COMPREHENSION # 1
The name 'Silica' covers an entire group of minerals, which have the general formula $$ \displaystyle SiO_{2}$$, The most common of which is quartz. Quartz is a framework silicate with $$ \displaystyle SiO_{4}$$ tetrahedral arranged in spirals. the spirals can turn in a clockwise or anticlockwise direction a feature that results in there being two mirror images, optically active, varieties of quartz.
The following pictures represent various silicate anions. Their formulae are respectively :

A
$$ \displaystyle { SiO }_{ 3 }^{ 2- } S{ i }_{ 3 }{ O }_{ 7 }^{ 2- }$$

B
$$ \displaystyle { SiO }_{ 4 }^{ 4- } S{ i }_{ 3 }{ O }_{ 10 }^{ 8- }$$

C
$$ \displaystyle { SiO }_{ 4 }^{ 2- } S{ i }_{ 3 }{ O }_{ 9 }^{ 2- }$$

D
$$ \displaystyle { SiO }_{ 3 }^{ 4- } S{ i }_{ 3 }{ O }_{ 7 }^{ 8- }$$

Solution

One silicon is bonded to four oxygen ions. No. of edges represents no. of oxygen ions.
The basic unit of silicates is $$SiO_{4} ^{4-}$$ in which number of shared $$O_{2}$$ units is 0.
The second silicate anion has 2 shared $$O_{2}$$ units. Therefore, its formula will be $$Si_{3} O_{10} ^{-8}$$.
Question 9
1 / -0

Identify the only 'INCORRECT' statement of the following.

A
B - O - B bonds in sodium peroxoborate are similar

B
B-O-B bonds in potassium trioborate are 3

C
Ortho borate ion is triangular plannar

D
B -O-B bonds in diborate ion is 1.

Solution

Structure of sodium peroxoborate. There is no B-O-B bond.
Question 10
1 / -0

Which of the following silicates contains cyclic structure ?

A
Zeolite

B
Asbestos

C
Emerald

D
Talc

Solution