Physical Properties of Boron Family

Q. The reaction of $H_3{N}_3{B}_{3}C{l}_3\left(A\right)$ with $LiB{H}_4$ in tetrahydrofuran gives $\left(B\right)$. Further, the reaction of $\left(A\right)$ with $\left(C\right)$ leads to $H_3{N}_3{B}_3(Me{)}_3$. Compounds $\left(B\right)$ and $\left(C\right)$ respectively, are:

1. Borazine and MeBr
2. Borazine and MeMgBr
3. Boron nitride and MeBr
4. Diborane and MeMgBr

Q.

In which of the following elements +1 oxidation state is more stable than +3 oxidation state?

1. Tl

2. Ga

3. Al

4. In

Q.

The element which exists as a liquid upto ${2000}^{\circ }C\&$ can be used in high temperature thermometry is

1. B

2. Al

3. Ga

4. In

Q.

Which of the following statements is false?

1. The sums of the three ionization enthalpies of each group 13 element follow the order

   $B>Al>Ga>In<Tl$

2. The stability of +3 oxidation state in group 13 elements follows the order.

   $B>Al>Ga>In>Tl$

3. The correct order of atomic radii of group 13 elements is

   $B<Al<Ga<In<Tl$

4. Group 13 consists of p-block elements

Q.

Which of the following is/are semiconductors?

1. B

2. Ga

3. Si

4. Al

Q.

$Al\&Ga$ have nearly the same constant radii because of

1. Greater shielding effect of s electrons of Ga atoms

2. Poor shielding effect of s electrons of Ga atoms

3. Greater shielding effect of d electrons of Ga atoms

4. Poor shielding effect of d electrons of Ga atoms

Q.

Soft heavy metal melts at 30${}^{\circ }$ C and is used in making heat sensitive thermometers the metal is

1. Galium

2. Sodium

3. Potassium

4. Caesium

Q.

The order in which the atomic radius increases is as follows

1. 
2. 
3. 
4. 

Q.

Both the amorphous and crystalline forms of boron are very reactive in air.

1. True

2. False

Q.

In the extraction of aluminium, the function of cryolite is to:

1. Remove impurities from alumina

2. Lower the melting point of alumina

3. Minimise the anodic effect

4. Increase the melting point of alumina