31.

Which method is not used for the extraction of Al ?

• Van - Arkel

• Serpeck

• Baeyer

• Hall - Heroult

Aluminium becomes passive on treatment with :

• dil. HNO₃

• conc. HNO₃

• dil. H₂SO₄

• none of these

A lyophobic colloid is :

• As₂S₃

• starch

• agar - agar

• gelatin

Which of the following is correct according to Freundlich adsorption isotherm ?

• $\frac{\mathrm{x}}{\mathrm{m}}$ $\propto$ p^o

• $\frac{\mathrm{x}}{\mathrm{m}}$ $\propto$ p

• $\frac{\mathrm{x}}{\mathrm{m}}$ $\propto$ $\frac{1}{\mathrm{p}}$

• $\frac{\mathrm{x}}{\mathrm{m}}$ $\propto$ p^1/n

The rust of iron is catalysed by which of the following ?

• Fe

• O₂

• Zn

• H⁺

HF is not preserved in glass bottle because :

• it reacts with the visible part of the light

• it reacts with the sodium oxide of the glass

• it reacts with the aluminium oxide of the glass composition

• it reacts with SiO₂ of the glass

Oils can be converted into fats by :

• hydrogenolysis

• hydrogenation

• decarboxylation

• hydration

In a lead storage battery , reaction at cathode is :

• Pb + SO₄^2- $\to$ PbSO₄ + 2e^-

• Pb + PbO₂ + 2H₂SO₄ $\to$ 2PbSO₄ + 2H₂O

• PbSO₄ + 2e^- $\to$ Pb + SO₄^2-

• PbO₂ + 4H⁺ + SO₄^2- + 2e^- $\to$ PbSO₄ + 2H₂O

In coagulating the colloidal solution of As₂S₃ .which has the minimum coagulating value ?

• NaCl

• KCl

• BaCl₂

• AlCl₃

Which radioactive element is being used in cancer therapy ?

• ${}_{27}{}^{60}\mathrm{Co}$

• ${}_{28}{}^{62}\mathrm{Ni}$

• ${}_{56}{}^{140}\mathrm{Ba}$

• ${}_{15}{}^{32}\mathrm{P}$