Which one of the following elements is unable to form ${\mathrm{MF}}_6^{3-}$ ion?

1. Ga

2. Al

3. B

4. In

Aluminium is extracted from alumina Al₂O₃  by electrolysis of a molten mixture of

1. ${\mathrm{Al}}_2{\mathrm{O}}_3+\mathrm{HF}+{\mathrm{NaAlF}}_4$

2. ${\mathrm{Al}}_2{\mathrm{O}}_3+{\mathrm{CaF}}_2+{\mathrm{NaAlF}}_4$

3. ${\mathrm{Al}}_2{\mathrm{O}}_3+{\mathrm{Na}}_3{\mathrm{AlF}}_6+{\mathrm{CaF}}_2$

4. ${\mathrm{Al}}_2{\mathrm{O}}_3+\mathrm{KF}+{\mathrm{Na}}_3{\mathrm{AlF}}_6$

The tendency of BF₃, BCl₃ and BBr₃ to behave as Lewis acids decreases in the sequence:

1. $BC{l}_3>B{F}_3>BB{r}_3$

2. $BB{r}_3>BC{l}_3>B{F}_3$

3. $BB{r}_3>B{F}_3>BC{l}_3$

4. $B{F}_3>BC{l}_3>BB{r}_3$

The stability of +1 oxidation state increases in the sequence

1. Al <Ga<In<Tl

2. Tl<In<Ga<Al

3. In<Tl<Ga<Al

4. Ga<In<Al<Tl

The most characteristic oxidation state for lead and tin is, respectively,:

1. +4, +2

2. +2, +4

3. +4, +4

4. +2, +2

An anion present in the chain structure silicate is -

1. ${\mathrm{Si}}_2{\mathrm{O}}_7^{6-}$

2. ${\left({\mathrm{Si}}_2{\mathrm{O}}_5^{2-}\right)}_{\mathrm{n}}$

3. ${\left({\mathrm{SiO}}_3^{2-}\right)}_{\mathrm{n}}$

4. ${\mathrm{SiO}}_4^{4-}$

${}_{}$
\(\mathrm{Al}_2 \mathrm{O}_3\) reacts with-

In the structure of borax, the numbers of boron atoms and B-O-B units, respectively, are

1.  4 and 5

2.  4 and 3

3.  5 and 4

4.  5 and 3

Hydrolysis of ${\mathrm{BCl}}_3$ gives X which on treatment with sodium carbonate produces Y. X and Y, respectively, are 

1.  ${\mathrm{H}}_3{\mathrm{BO}}_3 \mathrm{and} {\mathrm{NaBO}}_2$

2.  ${\mathrm{H}}_3{\mathrm{BO}}_3 \mathrm{and} {\mathrm{Na}}_2{B}_4{O}_7$

3.  ${\mathrm{B}}_2{\mathrm{O}}_3 \mathrm{and} {\mathrm{NaBO}}_2$

4.  $B_2{O}_3 \mathrm{and} {\mathrm{Na}}_2{B}_4{O}_7$