Chemistry - Adsorption and Colloids
Exam Duration: 45 Mins Total Questions : 30
Colloidal solutions of gold prepared by different methods are of different colours because of
- (a)
different diameters of colloidal gold particles
- (b)
Variable valency of gold
- (c)
different concentration of gold particles
- (d)
impurities produced by different methods
Milk is a/an
- (a)
Solution
- (b)
gel
- (c)
emulsion
- (d)
foam
Gold number of a lyophilic sol is such property that
- (a)
the larger its value, the greater is the peptising power
- (b)
the lower its value , the greater is the preptising power
- (c)
the lower its value, the greater is the protecting power
- (d)
the larger its value, the greater is the protecting power
Of which of the following colloids systems, fog is an example?
- (a)
liquid dispersed in gas
- (b)
gas dispersed in gas
- (c)
solid dispersed in gas
- (d)
solid dispersed in liquid
Soking of water by a sponge is an example of
- (a)
simple adsorption
- (b)
physical adsorption
- (c)
chemisorption
- (d)
adsorption
Colloids are
- (a)
homogeneous
- (b)
heterogenous
- (c)
true solutions
- (d)
suspensions
Which one of the following satements is false for hydrophilic sols?
- (a)
They do not require electrolytes for stability
- (b)
Their coagulation is reversible
- (c)
Their viscosity is of the orderof that of water
- (d)
Their surface tension is usually lower then that of dispersion medium
An emulsifier is an agent which
- (a)
accelerates the dispersion
- (b)
homogenises an emulsion
- (c)
stabilises an emulsion
- (d)
aids the flocculation of an emulsion
The stability of lyophilic colloids is due to
- (a)
charge on their particles
- (b)
a layerof medium of dispersion on their particles
- (c)
the smaller size of their particles
- (d)
the large size of their particles
According to Langmuir adsorption isotherm, the amount of gasadsorbed at very high pressures
- (a)
reaches a constant limiting value
- (b)
goes on increasing with pressure
- (c)
goes on decreasing with pressure
- (d)
increases first and decreases later with pressure
Which one of the following catalysts is used for polymerisation of alkenes?
- (a)
Ph3P)3 RhCl
- (b)
TiCl4 and (C2 H5)3Al
- (c)
ZnO + CuO
- (d)
V2O5
Pick out the increect satement :
- (a)
Colloidal particles have large surface area
- (b)
Colloidal particles pass through the pores of a filter paper
- (c)
Colloidal particles are charged particles
- (d)
Colloidal particles are netural
At CMC the surfactant molecules
- (a)
decomposes
- (b)
become completely soluble
- (c)
associates
- (d)
dissociates
Alum helps in purifying water by
- (a)
forming complex with clay particles
- (b)
the sulphate present in alum combines with the dirt and removes it
- (c)
aluminium coagulates the mud particles
- (d)
making mud water soluble
When colloidal solution passes through ordinary filter paper, then the observation obtained is
- (a)
it completely passes through ordinary filter paper
- (b)
it does not passes through ordinary filter paper
- (c)
it partially passes through ordinary filter paper
- (d)
None of the above
Which of the following is a best example of associated colloid?
- (a)
Protein in water
- (b)
Soap in water above CMC
- (c)
Rubber in benzene
- (d)
FeCl3 in H2O
Emulsion are prepared by
- (a)
shaking two liquids which are miscible
- (b)
shaking two liquids which are immiscible
- (c)
Both (a) and (b)
- (d)
None of the above
Which of the following is correct for emulsion?
- (a)
Emulsion are colourless
- (b)
Emulsion are generally coloured
- (c)
Emulsion is stable
- (d)
None of the above
Amongst the electrolytes Na2SO4, CaCl2, Al2(SO4)3 and NH4Cl, the most effective coagulating agent for Sb2S3 sol is.
- (a)
Na2SO4
- (b)
CaCl2
- (c)
Al2(SO4)3
- (d)
NH4Cl
Gold number of protective colloids A, B, C and D are 0.50, 0.01, 0.10 and 0.005 respectively. The correct order of their protective power is
- (a)
D < A < C < B
- (b)
C < B < D < A
- (c)
A < C < B < D
- (d)
B < D < A < C
Extent of adsorption is
- (a)
temperature dependent
- (b)
pressure dependent
- (c)
surface area dependent
- (d)
All of the above
The role of the activated charcoal in gas mask used coal mine is
- (a)
adsorption of poisonous gases
- (b)
adsorption of poisonous gases
- (c)
neutralisation of gases
- (d)
None of the above
Adsorption o gaseous molecules of hydrogen on Pd is known as
- (a)
reduction
- (b)
occlusion
- (c)
hydration
- (d)
hydrogenation
In physisorption, the molecules o adsorbate held to the adsorbent by
- (a)
chemical forces
- (b)
ionic forces
- (c)
van der Waals' forces
- (d)
None of the above
Physisorption is exothermic in nature because
- (a)
\(\Delta H<0\)
- (b)
\(\Delta H>0\)
- (c)
\(\Delta H=0\)
- (d)
None of these
The correct relationship which represents the Freundlich adsorption isotherm is
- (a)
\(log({x\over m})=logk+{1\over n}log p\)
- (b)
\(log({m\over x})=logk+{1\over n}log p\)
- (c)
\(log({x\over m})=logp+{1\over K}log p\)
- (d)
\(log({x\over m})=logc+{1\over n}log k\)
Powdered substances are more effective adsorbents than their cystalline form because
- (a)
crystalline form has more surface area than powdered form
- (b)
powdered form has more surface area than crystalline form
- (c)
crystalline form adsorbs in low temperature but powdered form requires high temperature
- (d)
None of the above
On the basis of the following data predict, which of following gas show least adsorption on a definite amount of charcoal?
Gas | CO2 | SO2 | CH4 | H2 |
Tc(K) | 304 | 630 | 190 | 33 |
- (a)
CO2
- (b)
SO2
- (c)
CH4
- (d)
H2
Point out the correct statement for chemisorption.
- (a)
It is exothermic and monolayered
- (b)
It is endothermic and monolayered
- (c)
It has enthalpy of adsorption in between 0-5kal mol-1
- (d)
All of the above
In general H2 gas is adsorbed on activated charcoal to a less extent in comparison to the easily liquefiable gases due to
- (a)
very strong van der Waals' force and low critical temperature
- (b)
very weak van der Waals' force and low critical temperature
- (c)
very strong van der Waals' force and high critical temperature
- (d)
very weak van der Waals' force and high critical temperature