Tag: study of diborane

Questions Related to study of diborane

Boron can undergo the following reactions with the given enthaly changes:
Assume no other reactions are occurring. If in a container (operating at constant pressure) which is isolated from the surrounding, mixture of are passed over excess of B(s), then calculate the molar ratio so that temperature of the container do not change :
${\text{2B}}\left( {\text{s}} \right){\text{ + }}\dfrac{{\text{3}}}{{\text{2}}}{{\text{O}} _{\text{2}}}\left( {\text{g}} \right) \to {{\text{B}} _{\text{2}}}{{\text{O}} _{\text{3}}}\left( {\text{s}} \right);\;\Delta H =  - 1260\;KJ$
${\text{2B}}\left( {\text{s}} \right){\text{ + 3}}{{\text{H}} _{\text{2}}}\left( {\text{g}} \right) \to {{\text{B}} _2}{H _6}\left( g \right);\;\Delta H = 30KJ$

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

  1. 15 : 3

  2. 42 : 1

  3. 1 : 42

  4. 1 : 84

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Correct Option: C

Moissan boron is:

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

  1. 95 - 98% pure amorphous boron

  2. 75 - 78% pure amorphous boron

  3. 95-98% pure crystalline boron

  4. 75 - 78% pure crystalline boron

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Correct Option: A
Explanation:

Moissan Boron is amorphous Boron of ultra high purity.

For healthy growth of plants, boron is an essential:

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

  1. minor nutrient

  2. major nutrient

  3. both

  4. major metal

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Correct Option: A
Explanation:

Boron is essential for the growth of higher plants. The primary function of the element is to provide structural integrity to the cell wall in plants. 


Other functions likely include the maintenance of the plasma membrane and other metabolic pathways.

So it is essential micronutrient for plants.

Option A is correct.

Which of the following is used as control rods in nuclear reactors?

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

  1. Al

  2. Ga

  3. Tl

  4. B

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Correct Option: D
Explanation:

Boron carbide is used as a control rod material.

Diborane undergoes cleavage and gives aduct with
(i) CO
(ii) $ H _2O $
(iii) $ N(Me) _3 $
(iv) $ NH _3 $

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

  1. i, ii

  2. i, iii

  3. ii, iii

  4. i, iv

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Correct Option: A

Borazole is an isoster of

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

  1. Benzene

  2. Propane

  3. Naphthalene

  4. Phenol

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Correct Option: A
Explanation:

Both have number of electrons and similar structure and properties.
Isosteres are molecules or ions of similar size containing the same number of atoms and valence electrons, e.g., O^2-, F-, Ne.

Diborane does not react with?

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

  1. $Cl _{2}$

  2. $Br _{2}$

  3. $I _{2}$

  4. all

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Correct Option: C

The number of simple covalent bonds (B-H) present in diborane:

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

  1. 2

  2. 4

  3. 6

  4. 8

Show answer
Correct Option: B
Explanation:
The molecular formula of diborane is $B _{2}H _{6}$
Diborane consists 2 3center-2electrons bonds and 4 2center-2electrons bonds.
In diborane, the two boron groups are bonded to each other by a bridge-like structure. Thus, it contains 4 covalent bonds.

Which of the following statement is correct for diborane ?

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

  1. Small amines like $NH _3,\, CH _3NH _2$ give unsymmetrical cleavage of diborane

  2. Large amines such as $(CH _3) _3N$ and pyridine gives symmetrical cleavage of diborane

  3. Small as well as large amines both gives symmetrical cleavage of diborane

  4. (A) and (B) both

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Correct Option: D
Explanation:

$Small\quad amines\ { B } _{ 2 }{ H } _{ 6 }+{ 2NH } _{ 3 }\rightarrow [{ H } _{ 2 }B\left( { NH } _{ 3 } \right) _{ 2 }]^{ + }[{ BH } _{ 4 }]^{ - }\ Large\quad amines\ { B } _{ 2 }{ H } _{ 6 }+2N\left( { CH } _{ 3 } \right) _{ 3 }\rightarrow 2{ H } _{ 3 }B\leftarrow N\left( { CH } _{ 3 } \right) _{ 3 }$

Which one of the following statement is not true regarding $B _2H _6$ ?

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

  1. It react with $NaH$ to form $NaBH _4$

  2. It is highly inflamable gas

  3. It contain four equal $B-H$ bonds

  4. It react with lewis base to form always adduct

Show answer
Correct Option: C
Explanation:

${B} _{2}{H} _{6}$ + $2NaH$ $\rightarrow$ $2 Na(B{H} _{4})$

It is highly Inflamable Gas and it reacts with Lewis base to form always adduct
It Doesn't contain 4 equal B-H bonds
So Option C is correct.