The sharp decrease in ionization enthalpy from carbon to silicon happens because of-

1.	Decrease in the charge of elements upon moving down the group.
2.	Decrease in the atomic sizes of elements upon moving down the group.
3.	Increase in the atomic sizes of elements upon moving down the group.
4.	Increase in the charge of elements upon moving down the group.

The correct explanation for the lower atomic radius of Ga as compared to Al is -

1. Poor shielding effect of the 2d-electrons

2. Poor shielding effect of the 3d-electrons

3. Poor shielding effect of the 3p-electrons

4. Poor shielding effect of the 2s-electrons

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