The p-Block Elements Test

Result

The p-Block Elements Test - 31

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Weekly Quiz Competition

Question 1
1 / -0

The butter of tin is represented by:

A
$$SnCl_2.\, 5H_2O$$

B
$$SnCl_2$$

C
$$SnCl_4$$

D
$$SnCl_4.\, 5H_2O$$

Solution

Tin(IV) chloride pentahydrate is butter of tin. It is represented as $$[SnCl_{4}\left( {H}_{2}O\right) _{2}]\cdot 3{H}_{2}O$$ or $$SnCl_4.5H_2O$$.
Question 2
1 / -0

Which of the following compound is a gas (at $$0^{\circ}C$$) ?

A
$$BF_3$$

B
$$BCI_3$$

C
$$BBr_3$$

D
$$BI_3$$

Solution

Mp(°C) Bp(°C)
$$BF_3$$ -126.8 -100.3
$$BCl_3$$ -107.3 12.6
$$BBr_3$$ -46.3 91.3
$$BI_3$$ 49.9 210

At $$\displaystyle 0^0C$$, $$\displaystyle BF_3$$ is a gas whereas $$\displaystyle BCl_3$$ and $$\displaystyle BBr_3$$ are liquids and $$\displaystyle BI_3$$ is a solid.
Question 3
1 / -0

When orthoboric acid $$(H_3BO_3)$$ is heated the residue left is:

A
Boron

B
Metaboric acid

C
Boric anhydride

D
Borax

Solution

B. Metaboric acid
Boric acid when heated above 170C it dehydrates forming metaboric acid. Metaboric acid when heated above 300C it further dehydrates forming pyroboric acid.
$${ H }_{ 3 }{ BO }_{ 3 }\rightarrow { HBO }_{ 2 }+{ H }_{ 2 }O\\ { 4HBO }_{ 2 }\rightarrow { H }_{ 2 }{ B }_{ 4 }{ O }_{ 7 }+{ H }_{ 2 }{ O }$$
Question 4
1 / -0

Correct trend of first lonisation energy in group 13 is:

A
$$\displaystyle B> Tl> Ga> Al> In$$

B
$$\displaystyle B> Al> Ga> Tl> In$$

C
$$\displaystyle B> Tl> Ga> Al> In$$

D
$$\displaystyle B> Ga> Al> In> Tl$$
Question 5
1 / -0

(a) Silicone is a polymeric organo silicon compound which is chemically inert and thermally stable
(b) Silicon carbide can be used as a lubricant.
(c) Silicon dioxide is the raw material for the manufacture of cement as well as glass.
(d) Hardness of $$Si{O}_{2}$$ and $$SiC$$ is due to their regular tetrahedral structure.

Which of the following regarding silicon and its compounds is correct?

A
a and b

B
b and c

C
a, c and d

D
only d

Solution

Silicones are polymers that include any inert, synthetic compound made up of repeating units of siloxane, which is a functional group of two silicon atoms and one oxygen atom frequently combined with carbon and/ or hydrogen. Silicon carbide found in the form of powder and grains. Silicon dioxide is the raw material for the manufacture of cement as well as glass Hardness of $$SiO_2$$ and $$SiC$$ is due to tetrahedral $$sp^3$$ bonds, one might expect the diamond structure
Question 6
1 / -0

An ecologist studied the effects of sewage effluent on the levels of oxygen concentration, bacterial population and algal growth in a fresh water stream. The given graph is plotted based on his findings.
select the correct statement regarding the given graph.

A
There is a fall in oxygen concentration between point Y and 4 km downstream because it is utilized by algae for respiration during day.

B
There is a rise in oxygen concentration between 4 km and 8 km downstream because of oxygen for respiration is lower

C
Bacterial population never recovers from 8 km onwards because all the oxygen is used by algae

D
There is decrease in the level of bacteria between 5 km and 7 km downstream because all the oxygen and organic matter has been used up by algal population

Solution

There is a rise in oxygen concentration between 4 km and 8 km downstream because bacterial usage of oxygen for respiration and for decomposition is lower.
Question 7
1 / -0

An aqueous solution of borax is :

A
neutral

B
amphoteric

C
basic

D
acidic

Solution

$$\bf{Hint:}$$ An aqueous solution which contains excess $$OH^{-}$$ ions are basic in nature.

$$\bf{Explanation:}$$

Borax also called as sodium tetraborate and its chemical formula is $$Na_2B_4O_7$$.

The complete reaction of borax with water is as shown below;
$$\bf\displaystyle Na_2B_4O_7+7H_2O \rightarrow 2NaOH+4H_3BO_3 $$

In the reaction, there is a formation of sodium hydroxide $$NaOH$$ which is a strong base, and boric acid $$H_3BO_3$$ which is a weak acid.
As there is a strong base and weak acid formed in the reaction overall solution becomes basic in nature.

$$\bf{Final \ answer:}$$ Option $$C$$
Question 8
1 / -0

Borosilicate glasses are used as laboratory wares because of:

A
low thermal expansion

B
high thermal expansion

C
high refractive index

D
low refractive index

Solution

Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glassesware known for having very low coefficients of thermal expansion $$(3 106 /^oC)$$ at $$(20^oC)$$, making them resistant to thermal shock, more so than any other common glass.
Question 9
1 / -0

Which of the following is a water-borne disease :

A
Malaria

B
Dysentery

C
Pneumonia

D
Breathlessness

Solution

Water borne diseases are caused by micro organisma in untreated contaminated water.
ex. Cholera,Dysentery.
Question 10
1 / -0

Pnicogens are the elements of group:

A
$$15$$

B
$$13$$

C
VIII

D
Zero

Solution

Members of group $$15$$ or VA of Periodic Table are called pnicogens. They include $$N,\ P,\ As,\ Sb$$ and $$Bi$$.

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	Mp(°C)	Bp(°C)
$$BF_3$$	-126.8	-100.3
$$BCl_3$$	-107.3	12.6
$$BBr_3$$	-46.3	91.3
$$BI_3$$	49.9	210

The p-Block Elements Test - 31

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The p-Block Elements Test - 31

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Question 1

$$SnCl_2.\, 5H_2O$$

$$SnCl_2$$

$$SnCl_4$$

$$SnCl_4.\, 5H_2O$$

Solution

Question 2

$$BF_3$$

$$BCI_3$$

$$BBr_3$$

$$BI_3$$

Solution

Question 3

Boron

Metaboric acid

Boric anhydride

Borax

Solution

Question 4

$$\displaystyle B> Tl> Ga> Al> In$$

$$\displaystyle B> Al> Ga> Tl> In$$

$$\displaystyle B> Tl> Ga> Al> In$$

$$\displaystyle B> Ga> Al> In> Tl$$

Question 5

a and b

b and c

a, c and d

only d

Solution

Question 6

There is a fall in oxygen concentration between point Y and 4 km downstream because it is utilized by algae for respiration during day.

There is a rise in oxygen concentration between 4 km and 8 km downstream because of oxygen for respiration is lower

Bacterial population never recovers from 8 km onwards because all the oxygen is used by algae

There is decrease in the level of bacteria between 5 km and 7 km downstream because all the oxygen and organic matter has been used up by algal population

Solution

Question 7

neutral

amphoteric

basic

acidic

Solution

Question 8

low thermal expansion

high thermal expansion

high refractive index

low refractive index

Solution

Question 9

Malaria

Dysentery

Pneumonia

Breathlessness

Solution

Question 10

$$15$$

$$13$$

VIII

Zero

Solution

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