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

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 incorrect statement among the following options is-

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 

Incorrect statement among the following options is :