During osmosis, flow of water through a semi-permeable membrane is

• from both sides of semi-permeable membrane with equal flow rate

• from solution having lower concentration only

• from solution having higher concentration only

• None of the above

In electrolysis of NaCl when Pt electrode is taken then H₂ is liberated at cathode while with Hg electrode it forms sodium amalgam

• Hg is more inert than Pt

• more voltage is required to reduce H⁺ at Hg than at Pt

• Na is dissolved in Hg while it does not dissolve in Pt

• concentration of H⁺ ions is larger when Pt electrode is taken

63.

On the basis of the information available from the reaction,

$\frac{4}{3}\mathrm{Al} + {\mathrm{O}}_2 \to \frac{2}{3} {\mathrm{Al}}_2{\mathrm{O}}_3$

$∆$G = -827 kJ mol^-1 of O₂, the minimum emf required to carry out an electrolysis of Al₂O₃ is (F = 96500 mol^-1)

• 2.14 V

• 4.28 V

• 6.42 V

• 8.56 V

4.5 g of aluminium (atomic mass 27 u) is deposited at cathode from Al³⁺ solution by a certain quantity of electric charge. The volume of hydrogen produced at STP from H⁺ ions in solution by the same quantity of electric charge will be

• 44.8 L

• 11.2 L

• 22.4 L

• 5.6 L

The time of completion of 90% of a first order reaction is approximately

• 1.1 times that of half-life

• 2.2 times that of half-life

• 3.3 times that of half-life

• 4.4 times that of half-life

The rate of reaction between two reactants A and B decreases by a factor of 4, if the concentration of reactant B is doubled. The order of this reaction with respect to reactant B is

• 2

• -1

• 1

• -2

In a first-order reaction A → B, if k is rate constant and initial concentration of reactant A is 0.5 M then, the half-life is

• $\frac{\ln 2}{\mathrm{k}}$

• $\frac{0.693}{0.5}$

• $\frac{\log 2}{2\mathrm{k}}$

• $\frac{\log 2}{\mathrm{k} \sqrt{0.5}}$

Which ion is colourless?

• Cr⁴⁺

• Sc³⁺

• Ti³⁺

• V⁴⁺

Which of the following statement is not correct?

• La(OH)₃ is less basic than Lu(OH)₃.

• In lanthanide series ionic radius of Lu³⁺ ion decreases.

• La is actually an element of transition series rather lanthanide.

• Atomic radius of Zr and Hf are same because of lanthanide contraction.

Four successive members of the first row transition elements are listed below with their atomic numbers. Which one of them is expected to have the highest third ionisation enthalpy? 

• Vanadium (Z = 23)

• Manganese (Z = 25)

• Chromium (Z= 24)

• Iron (Z = 26)