Which of the following oxides is amphoteric in nature?

1. CO₂

2. CO

3. SnO₂

4. CaO

Which of the following elements does not show a significant inert pair effect?

1. Aluminium (Al)

2. Tin (Sn)

3. Lead (Pb)

4. Thallium (Tl)

The reagent that is used to remove ${\mathrm{SO}}_4^{2-}$ and Cl^- is -

1. NaOH             

2. Pb(NO₃)₂

3. BaSO₄             

4. KOH

Borax is converted into crystalline boron by the following steps:

          $\mathrm{Borax}\stackrel{\mathrm{X}}{\to }{\mathrm{H}}_3{\mathrm{BO}}_3\stackrel{∆}{\to }{\mathrm{B}}_2{\mathrm{O}}_3\underset{∆}{\overset{\mathrm{Y}}{\to }}\mathrm{B}$

X and Y are respectively :

1. HCl, Mg                                 
2. HCl, C
3. C, Al 
4. HCl, Al

Which of the following statements regarding borax is incorrect?

1. Borax is used as a primary standard in acid–base titrations.

2. The tetraborate ion present in borax contains four B–O–B bridges.

3.  An aqueous borax solution can act as a buffer.

4. The tetraborate ion consists of two trigonal planar BO₃ units and two tetrahedral BO₄ units.

Find the species that does not exist among the following.
1. [SnF₆]²⁻
2. [GeCl₆]²⁻
3. [CCl₆]²⁻
4. [SiF₆]²⁻

$\mathrm{B}{\left(\mathrm{OH}\right)}_3+\mathrm{NaOH}\rightleftharpoons {\mathrm{NaBO}}_2+\mathrm{Na}\left[\mathrm{B}{\left(\mathrm{OH}\right)}_4\right]+{\mathrm{H}}_2\mathrm{O}$

 This reaction is made to proceed in forward direction by -

1. Addition of Cis- 1,2 diol

2. Addition of borax

3. Addition of trans 1,2- diol

4. Addition of ${\mathrm{Na}}_2{\mathrm{HPO}}_4$

Which of the following correctly explains why an aqueous solution of borax reacts with two moles of acid?

1. Formation of 2 moles of  B(OH)₃  only

2. Formation of 2 moles of  [B(OH)₄]^-  only

3. Formation of 1 mole each of  B(OH)₃ and [B(OH)₄]^-

4. Formation of 2 moles each of [B(OH)₄]^- and B(OH)₃, only [B(OH)₄]^-  reacts with an acid 

Aluminium becomes passive in nitric acid because it-

1. Is a noble metal

2. Forms a thin film of oxide

3. Has a positive reduction potential

4.  None of the above

Borax bead test is responded by:

1.  Divalent metals

2.  Heavy metals

3.  Light metals

4.  Metal which forms coloured metaborates