The best method for the separation of naphthalene and benzoic acid from their mixture is
chromatography
crystallisation
distillation
sublimation
D.
sublimation
The best method for the separation of naphthalene and benzoic acid from their mixture is sublimation because it is applicable for those organic compounds which pass directly from solid to vapour state on heating and vice-versa on cooling. In these compounds naphthalene is volatile and benzoic acid is non-volatile due to the formation of dimer via hydrogen bonding (intermolecular).
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 pH3 > pH4
pH1 < pH2 pH3 < pH4
pH1 < pH2 pH3 pH4
pH1 > pH2 pH3 > pH4
For a first order reaction A 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
A solution of urea (mol. mass 56g mol-1) boils at 100.18°C at the atmospheric pressure. If kf and kb 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