21.

The time period to coat a metal surface of 80 cm² with 5 x 10^-3 cm thick layer of silver (density 1.05 g cm^-3) with the passage of 3 A current through a silver nitrate solution is

• 115 sec

• 125 sec

• 135 sec

• 145 sec

Correct equation of Freundlich isotherm is

• $\log \left(\frac{\mathrm{x}}{\mathrm{m}}\right)= \mathrm{logk} + \frac{1}{\mathrm{n}}\log \mathrm{c}$

• $\log \left(\frac{\mathrm{x}}{\mathrm{m}}\right) = \log \mathrm{c}+\frac{1}{\mathrm{n}}\log \mathrm{k}$

• $\log \left(\frac{\mathrm{x}}{\mathrm{m}}\right)= \log \mathrm{c} +\frac{1}{\mathrm{k}} \log \mathrm{c}$

• $\log \left(\frac{\mathrm{x}}{\mathrm{m}}\right) = \mathrm{logk} + \frac{1}{\mathrm{k}}\log \mathrm{c}$

The flame colours of metal ions are due to

• Frenkel defect

• Schottky defect

• metal deficiency defect

• metal excess defect.

Acid hydrolysis of sucrose is a

• pseudo first order reaction

• zero order reaction

• second order reaction

• unimolecular reaction.

The number of S - S bonds in sulphur trioxide trimer (S₃O₉) is

• three

• two

• one

• zero

The root mean square speed of the molecules of diatomic gas is u. When the temperature is doubled, the molecules dissociate into two atoms. The new rms speed of the atom is

• $\sqrt{2\mathrm{u}}$

• u

• 2u

• 4u

For the following concentration cell, to be spontaneous Pt(H₂)P1 atm. |HCl | Pt(H₂)P₂ atm. Which of the following is correct?

• P₁=P₂

• P₁<P₂

• P₁>P₂

• Can't be predicted

Which one of the following is not a surfactant?

• 

• CH₃-(CH₂)₁₄-CH₂-NH₂

• CH₃-(CH₂)₁₆-CH₂OSO₂^-Na⁺

• OHC-(CH₂)₁₄-CH₂-COO^-Na⁺

The standard oxidation potential E° for the half cell reaction are

$$\begin{gathered} \mathrm{Zn} \to {\mathrm{Zn}}^{2+} + 2{\mathrm{e}}^{-}; \mathrm{E}°= + 0.76 \mathrm{V} \\ \mathrm{Fe}\to {\mathrm{Fe}}^{2+} + 2{\mathrm{e}}^{- }; {\mathrm{E}}^{°}= + 0.41 \mathrm{V} \\ \mathrm{EMF} \mathrm{of} \mathrm{the} \mathrm{cell} \mathrm{reaction} \mathrm{is} \\ \mathrm{Zn} + {\mathrm{Fe}}^{2+} \to {\mathrm{Zn}}^{2+} + \mathrm{Fe} \end{gathered}$$

• - 0.35 V

• + 0.35 V

• 0.17V

• 1.17V.

To observe the effect of concentration on the conductivity of electrolytes of different nature were taken in two vessels A and B. A contains weak electrolyte NH₄OH and B contains strong electrolyte NaCl. In both containers, concentration of respective electrolyte was increased and conductivity observed

•  in A conductivity increases, in B conductivity decreases

• in A conductivity decreases, while in B conductivity increases

• in both A and B conductivity increase

• in both A and B conductivity decreases.