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 

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

 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 ${\mathrm{Na}}_2{\mathrm{HPO}}_4$

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

Which of the following statements regarding germanium compounds is incorrect?

1. $\mathrm{Ge}{\left(\mathrm{OH}\right)}_2$ is amphoteric

2. ${\mathrm{GeCl}}_2$ is more stable than ${\mathrm{GeCl}}_4$

3. ${\mathrm{GeO}}_2$ is weakly acidic

4. GeCl₄ + 2HCl ⇄ H₂[GeCl₆]

Silicon carbide is used as:

The percentage of lead in a lead pencil is-

1.  20

2.  0

3.  80

4.  70

AlF₃ is soluble in HF only in the presence of KF due to the formation of:

Which of the following correctly describes  behavior of Sn²⁺ and Pb⁴⁺?

Which of the following Group 13 elements cannot form the hexafluoro complex ion [MF₆]³⁻?