21.

Names of some compounds are given. Which one is not correct in IUPAC system?

• $\underset{3-\mathrm{methyl}-2-\mathrm{butanol}}{{\mathrm{CH}}_3 - \mathrm{CH}\left(\mathrm{OH}\right) -\hspace{0.17em}\mathrm{CH}\left({\mathrm{CH}}_3\right) - {\mathrm{CH}}_3}$

• $\underset{4-\mathrm{methyl}-2-\mathrm{pentyne}}{{\mathrm{CH}}_3 - \mathrm{C}\equiv \mathrm{C} - \mathrm{CH}\left({\mathrm{CH}}_3\right)}$

• $\underset{2-\mathrm{ethyl}-3\mathrm{methyl}-\mathrm{but}-1-\mathrm{ene}}{{\mathrm{CH}}_3 - {\mathrm{CH}}_2 - \mathrm{C}\left({\mathrm{CH}}_2\right) - \mathrm{CH}\left({\mathrm{CH}}_3\right) -{\mathrm{CH}}_3}$

• 

The best method for the separation of naphthalene and benzoic acid from their mixture is

• chromatography

• crystallisation

• distillation

• sublimation

At 25°C, the dissociation constant of a base, BOH, is 1.0 x 10^-12. The concentration of
hydroxyl ions in 0.01 M aqueous solution of the base would be

• 2.0 x 10^-6 mo L^-1

• 1.0 x 10^-5 mo L^-1

• 1.0 x 10^-6 mo L^-1

• 1.0 x 10^-7 mo L^-1

The aqueous solution containing which one of the following ions will be colourless ? (Atomic no. Sc= 21, Fe= 26, Ti= 22, Mn = 25)

• Sc³⁺

• Fe²⁺

• Ti³⁺

• Mn²⁺

What is the correct relationship between the pHs of isomolar solutions of sodium oxide (pH₁), sodium sulphide (pH₂), sodium selenide (pH₃) and sodium telluride (pH₄)?

• pH₁ > pH₂ $\approx$pH₃ > pH₄

• pH₁ < pH₂ $<$pH₃ < pH₄

• pH₁ < pH₂ $<$pH₃ $\approx$ pH₄

• pH₁ > pH₂ $>$pH₃ > pH₄

For a first order reaction A $\to$ B, the reaction rate at reactant concentration of 0.01 M is found to be 2.0 x 10^-5 mol L^-1s^-1. The half-life period of the reaction is

• 220 s

• 30 s

• 300 s

• 347 s

Which one of the following forms micelles in aqueous solution above certain concentration?

• Urea

• Dodecyl trimethyl ammonium chloride

• Pyridinium chloride

• Glucose

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

• -1

• -2

• 1

• 2

In a face-centered cubic lattice, a unit cell is shared equally by how many unit cells?

• 8

• 4

• 2

• 6

A solution of urea (mol. mass 56g mol^-1) boils at 100.18°C at the atmospheric pressure. If k_f and k_b for water are 1.86 and 0.512 K kg mol^-1 respectively, the above solution will freeze at

• -6.54°C

• 6.54°C

• 0.654°C

• - 0.654°C