Amphoteric oxides are:

1. Tl₂O₃, SiO₂

2. ${\mathrm{CO}}_2$, ${\mathrm{B}}_2{\mathrm{O}}_3$

3. ${\mathrm{B}}_2{\mathrm{O}}_3$, ${\mathrm{SiO}}_2$

4. Al₂O₃ , PbO₂

When a metal X is treated with sodium hydroxide, a white precipitate (A) is obtained, which is soluble in excess of NaOH to give soluble complex (B). Compound (A) is soluble in dilute HCl and forms compound (C). The compound (A) when heated strongly gives (D), which is used to extract the metal.

X, C & D are respectively :

An aqueous solution of Borax is-

The hybridization of boron in diborane is-

1. sp

2. s${\mathrm{p}}^2$

3. s${\mathrm{p}}^3$

4. ds${\mathrm{p}}^2$

Thermodynamically the most stable form of carbon is-

The incorrect statement among the given options is :

When hydrated alumina is treated with an aqueous NaOH solution, it gives-

1. ${\mathrm{NaAlO}}_2$

2. $\mathrm{Na}\left({\mathrm{Al}}_2{\mathrm{O}}_3\right)$

3. ${\mathrm{NaAl}}_2\mathrm{O}$

4. Both (2) and (3)

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)