The correct reaction(s) among the following options is/are -

1. ${\mathrm{SiO}}_2$ $+\hspace{0.17em}4\mathrm{HF}$ $\to$ ${\mathrm{SiF}}_4$ $+$ $2{\mathrm{H}}_2\mathrm{O}$

2. $\mathrm{ZnO}$ $+$ $\mathrm{CO}$ $\to$ $\mathrm{Zn}$ $+\hspace{0.17em}{\mathrm{CO}}_2$

3. ${\mathrm{SiF}}_4$ $\hspace{0.17em}+$ $2\mathrm{HF}$ $\to$ ${\mathrm{H}}_2{\mathrm{SiF}}_6$

4. All of the above

The incorrect statement regarding allotropes/allotropy is :

The correct statement(s) regarding thallium is/are :

1. Thallium displays both +1, and +3 oxidation states.

2. It resembles group 1 metals in some reactions.

3. Thallium only shows a +1 oxidation state.

4. Both (1) and (2) 

Which statement among the following is incorrect?

Borax when heated strongly gives

1. ${\mathrm{Na}}_{}{\mathrm{BO}}_2$

2. ${\mathrm{B}}_2{\mathrm{O}}_3$

3. ${\mathrm{Na}}_2{\mathrm{O}}_2$

4. Both (1) and (2)

The correct statement(s) regarding diborane and boric acid is/are-

1. Diborane has two 3c-2e^- bonds.

2. Boric acid has a layered structure.

3. Four 2c-2e^- bonds are present in diborane.

4. All of the above

The incorrect statement among the following options is-

The correct statement(s) among the following options is/are:

Aluminum trifluoride is insoluble in anhydrous HF but dissolves on addition of NaF because:

The complex formed on reaction of Sodium hexafluoroaluminate(III) with BF₃ is -

1. $\mathrm{Na}\left[{\mathrm{BF}}_4\right]$

2. ${\mathrm{Na}}_2\left[{\mathrm{BF}}_4\right]$

3. $\mathrm{Na}{\left[{\mathrm{BF}}_4\right]}_2$

4. None of the above