The p-Block Elements Test

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The p-Block Elements Test - 29

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Weekly Quiz Competition

Question 1
1 / -0

Which of the following element does not show inert pair effect?

A
Tl

B
Pb

C
Bi

D
C

Solution

The inert pair effect is the tendency of the electrons in the outermost atomic s orbital to remain unionized or unshared in compounds of post-transition metals. The term inert pair effect is often used in relation to the increasing stability of oxidation states that are two less than the group valency for the heavier elements of groups 13, 14, 15 and 16. The inert pair effect is shown by Tl, Pb and Bi due to which, the lower oxidation state is more stable than the higher oxidation state. But C, being higher up in the periodic table, does not show inert pair effect.
Question 2
1 / -0

Silicones have the general formula :

A
$${SiO_{4}}^{4-}$$

B
$${Si_2O_{7}}^{6-}$$

C
$$(R_2SiO)_n$$

D
$${(SiO_3)_{n}}^{2-}$$

Solution

Organic polymers containing silicon in them are called as silicons. Silicons have general formula of $$R_2SiO$$, an empirical formula analogous to ketone $$(R_2CO)$$.
Question 3
1 / -0

Glass or silica soluble in:

A
$$HClO_4$$

B
$$HF$$

C
aqua-regia

D
$$H_2SO_4$$

Solution

Hydrofluoric acid has the ability to dissolve (most) oxides, glass and silicates
Question 4
1 / -0

$$CO_2$$ and $$SiO_2$$ is a solid or gas ?

A
$$CO_2$$ gas and $$SiO_2$$ solid

B
$$CO_2$$ solid and $$SiO_2$$ gas

C
$$CO_2$$ gas and $$SiO_2$$ gas

D
$$CO_2$$ solid and $$SiO_2$$ solid

Solution

If you look at the crystal structure of silicon dioxide, you will see it is comprised of tetrahedra (one silicon surrounded by 4 oxygen atoms) and these tetrahedra are in turn connected to each other, and subsequently form a 2-dimensional network which is large enough to make this substance a solid. The intermolecular forces within $$CO_2$$ are very weak, only comprised of London dispersion forces, thereby allowing for $$CO_2$$ to exist as a gas rather than a liquid or solid under standard conditions. $$SiO_2$$ on the other hand, has more of a metallic character since, silicon is a metalloid. The greater the ionic/metallic character of the substance, the greater the intermolecular forces will be. In addition to this, $$SiO_2$$ has a highly crystalline shape, allowing for maximum interaction between the atoms to allow for a rigid and unwavering shape, thereby allowing $$SiO_2$$ to form rigid bonds in a crystalline form.
Question 5
1 / -0

Statement - I: Silicones are very inert polymers.
Statement - II: Both Si-O and Si-C bond energies are very high.
Read the above statements and choose the correct option regarding it.

A
Statement-I is true, Statement-II is true ; Statement-II is correct explanation for Statement-I.

B
Statement-I is true, Statement-II is true ; Statement-II is not a correct explanation for Statement-I.

C
Statement-I is true, Statement-II is false.

D
Statement-I is false, Statement-II is true.

Solution

Option (A) is correct.
Silicones are very inert polymers.Both $$Si-O$$ and $$Si-C$$ bond energies are very high.
The bond energy of Si-O bond is 502 kJ/mol.
The chemical inertness is also due to stable silica like arrangement of Si-O-Si-O-Si.
Silicones are organosilicon polymers containing Si-O-Si linkages.
Question 6
1 / -0

Which variety of glass is used for manufacture of optical glasses ?

A
Sodium glass

B
Flint glass

C
Ground glass

D
Quartz

Solution

The most common types of glasses used in optics are crown glasses and flint glasses, designations based on their dispersions. Flint glasses contain lead. These designations are further subdivided by composition and have letter designations and number designations called "glass numbers".
Question 7
1 / -0

Which of the following silk fibre is soft, lustrous and elastic?

A
Tassar silk

B
Mooga silk

C
Kosa silk

D
Mulberry silk

Solution

Option $$(D)$$ is correct.
Mulberry silk fibre is soft, lustrous and elastic. It is most common silk fibre and can be dyed in beautiful colours.
Question 8
1 / -0

Assertion(A): $$Be$$ forms $$[BeF_4]^{2-}$$, but $$Al$$ forms $$[AlF_6]^{3-}$$.
Reason(R): $$Be$$ does not have d-orbitals in the valence shell but $$Al$$ has.

A

If both (A) and (R) are correct and (R) is the correct explanation of (A).

B
If both (A) and (R) are correct, but (R) is not the correct explanation of (A).

C
If (A) is correct, but (R) is incorrect.

D

If (A) is incorrect, but (R) is correct.
Question 9
1 / -0

The decrease in stability of higher oxidation states in p-block with increasing atomic number is due to :

A
increase in bond energy on going down the group

B
the reluctance of electrons of s-sub shell to participate in chemical bonding

C
poor screening effect of d-orbitals

D
none of the above

Solution

The inert pair effect is the tendency of the electrons in the outermost atomic s orbital to remain unionized or unshared in compounds of post-transition metals. Down the group in the p-block, the inert pair effect becomes more pronounced on account of enhanced increase in effective nuclear charge. Therefore, due to reluctance of electrons of s-subshell to participate in chemical bonding, there occurs a decrease in stability of higher oxidation states in p-block with increasing atomic number.
Question 10
1 / -0

The building units of various crystalline forms of boron are:

A
$$B_{12}$$ icosahedral units

B
$$B_4$$ tetrahedral units

C
$$B_6$$ octahedral units

D
$$B_6$$ cubical units

Solution

The building units of various crystalline forms of boron are $$B_{12}$$ icosahedral units.Icosahedron is a three dimensional space formed bt twenty equilateral triangles meeting at twelve vertices.All the twelve vertices of icosahedron are occupied by boron atoms to constitute $$B_{12}$$ unit.

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Re-Attempt Weekly Quiz Competition

The p-Block Elements Test - 29

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The p-Block Elements Test - 29

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SHARING IS CARING

Question 1

Tl

Pb

Bi

C

Solution

Question 2

$${SiO_{4}}^{4-}$$

$${Si_2O_{7}}^{6-}$$

$$(R_2SiO)_n$$

$${(SiO_3)_{n}}^{2-}$$

Solution

Question 3

$$HClO_4$$

$$HF$$

aqua-regia

$$H_2SO_4$$

Solution

Question 4

$$CO_2$$ gas and $$SiO_2$$ solid

$$CO_2$$ solid and $$SiO_2$$ gas

$$CO_2$$ gas and $$SiO_2$$ gas

$$CO_2$$ solid and $$SiO_2$$ solid

Solution

Question 5

Statement-I is true, Statement-II is true ; Statement-II is correct explanation for Statement-I.

Statement-I is true, Statement-II is true ; Statement-II is not a correct explanation for Statement-I.

Statement-I is true, Statement-II is false.

Statement-I is false, Statement-II is true.

Solution

Question 6

Sodium glass

Flint glass

Ground glass

Quartz

Solution

Question 7

Tassar silk

Mooga silk

Kosa silk

Mulberry silk

Solution

Question 8

If both (A) and (R) are correct and (R) is the correct explanation of (A).

If both (A) and (R) are correct, but (R) is not the correct explanation of (A).

If (A) is correct, but (R) is incorrect.

If (A) is incorrect, but (R) is correct.

Question 9

increase in bond energy on going down the group

the reluctance of electrons of s-sub shell to participate in chemical bonding

poor screening effect of d-orbitals

none of the above

Solution

Question 10

$$B_{12}$$ icosahedral units

$$B_4$$ tetrahedral units

$$B_6$$ octahedral units

$$B_6$$ cubical units

Solution

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