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A compound $A$ of boron reacts with $NMe _3$ to give an adduct $B$ which on hydrolysis gives a compound $C$ and a gas $D$. Compound $C$ is an acid.

Compound $C$ is :

chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

  1. diborane

  2. boric acid

  3. borate salt

  4. none of these

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Correct Option: B
Explanation:

     $B _2H _6+2NMe _3\longrightarrow 2BH _3.NMe _3$

Diborane (A)                        Adduct (B)

$BH _3.NMe _3+3H _2O\longrightarrow H _3BO _3+NMe _3+3H _2$
                                                Boric acid                     $\downarrow$
                                                      (C)                          (D) gas

Compound "C" is boric acid $-H _3BO _3$

A compound $A$ of boron reacts with $NMe _3$ to give an adduct $B$ which on hydrolysis gives a compound $C$ and a gas $D$. Compound $C$ is an acid.


Compound $A$ is :

chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

  1. diborane

  2. boric acid

  3. borate salt

  4. none of these

Show answer
Correct Option: A
Explanation:

     $B _2H _6+2NMe _3\longrightarrow2BH _3.NMe _3$

Diborane (A)                        Adduct (B)

$BH _3.NMe _3+3H _2O\longrightarrow H _3BO _3+NMe _3+3H _2$
                                               Boric acid                      $\downarrow$
                                                    (C)                            (D) gas
Compound $A$ is diborane.

Which of the following are used as catalyst in Friedal-craft reaction?

chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

  1. $AlCl _3$

  2. $SiCl _4$

  3. $BF _3$

  4. $SnCl _4$

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Correct Option: A,C,D
Explanation:

$Al{ Cl } _{ 3 },B{ F } _{ 3 },Sn{ Cl } _{ 4 }$ can be used as catalyst in Friedal Craft reaction.

An alkali metal hydride (NaH) react with diborane in 'A' to give a tetrahedral compound 'B' which is extensively used as reducing agent in organic synthesis. The compounds 'A' and 'B' respectively are :

chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

  1. $CH _3COCH _3\,\,\, and \,\,\,B _3N _3H _6$

  2. $(C _2H _5) _2O \,\,\,and\,\,\, NaBH _4$

  3. $C _2H _6\,\,\,and\,\,C _2H _5Na$

  4. $C _6H _6\,\,\,and\,\,\,NaBH _4$

Show answer
Correct Option: B
Explanation:
Answer:-
When an alkali metal hydride $(NaH)$ react with diborane $({B} _{2}{H} _{6})$ in the presence of ether $({({C} _{2}{H} _{5})} _{2}O)$, a tetrahedral compound (Metal borohydride) is formed which act as a reducing agent in organic synthesis.
$2NaH + {B} _{2}{H} _{6} \; \xrightarrow{{({C} _{2}{H} _{5})} _{2}O} \; \underset{\text{sodium borohydride}}{2NaB{H} _{4}}$
Thus, A is  ${({C} _{2}{H} _{5})} _{2}O$ and B is $NaB{H} _{4}$.

A compound $X$, of boron reacts with $NH _3$ on heating to give another compound $Y$ which is called inorganic benzene. The compound $X$ can be prepared by treating $BF _3$ with lithium aluminum hydride. The compounds $X$ and $Y$ are represented by formula:

chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

  1. $B _2H _6, B _3N _3H _6$

  2. $B _2O _3, B _3N _3H _6$

  3. $BF _3, B _3N _3H _6$

  4. $B _3N _3H _6, B _2H _6$

Show answer
Correct Option: A
Explanation:
A compound $X$, of boron, reacts with $N{H} _{3}$ on heating to give another compound $Y$ which is called inorganic benzene.
$\underset{X \; (Diborane)}{3{B} _{2}{H} _{6}} + 6N{H} _{3} \longrightarrow 3{[B{H} _{2}{(N{H} _{3})} _{2}]}^{+}{[B{H} _{4}]}^{-} \xrightarrow{heat} \underset{\text{Y (Borazole/Inorganic Benzene)}}{2{B} _{3}{N} _{3}{H} _{6}} + 12{H} _{2}$
$4B{F} _{3} + 3LiAl{H} _{4} \longrightarrow \underset{X}{2{B} _{2}{H} _{6}} +3LiF + 3Al{F} _{3}$

The styx number for $B _2H _6$ is:

chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

  1. $2012$

  2. $2222$

  3. $2002$

  4. $2102$

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Correct Option: C

Diborane undergoes cleavage and gives aduct with

chemistry the p-block elements - group 13 study of diborane some important compounds of boron study of boron

  1. CO

  2. $ H _2O $

  3. $ N(Me) _3 $

  4. $ NH _3 $

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Correct Option: D

Which of the following is not a greenhouse gas?

chemistry air and water pollution control environmental impact: global warming green house effect geobiochemical cycle

  1. Carbon dioxide

  2. Sulphur dioxide

  3. Methane

  4. Nitrogen

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Correct Option: D
Explanation:

Greenhouse gases present in the atmosphere trap the radiations and do not allow heat to leave. Examples of greenhouse gases include carbon dioxide, methane, sulphur dioxide.

Increased level of greenhouse gases causes global warming which will result in:

chemistry air and water pollution control environmental impact: global warming green house effect geobiochemical cycle

  1. biomagnification

  2. eutrophication

  3. melting of glaciers

  4. ozone depletion

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Correct Option: C
Explanation:

The earth's atmosphere traps the heat from the sun, preventing it from escaping into space is the greenhouse effect. This is mainly caused by deforestation. This results in an increase in average temperature of the atmosphere due to which glaciers start melting and there is a rise in sea level. 

Which of the following is not a refrigerant?

chemistry pollution of air and water environmental impact: global warming green house effect geobiochemical cycle

  1. $CHClF _{2}$

  2. $NH _{3}$

  3. $Ether$

  4. $C _{2}H _{4}$

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Correct Option: D
Explanation:

Ethene is a colorless flammable gas with a faint "sweet and musky" odor when pure.
Ethylene is widely used in chemical industry. Ethylene is also an important natural plant hormone, used in agriculture to force the ripening of fruits. it is a non refrigerant.