Chemistry M.C.Q (1 Marks)

A germ pore is a small pore in the outer wall of fungal pore which is used for initiation of pollen tube.

It is a well known fact that the metal used as a catalyst in the hydrogenation of oil is nickel.

River water is a colloidal solution of clay. Sea water contains a number of electrolytes. When river water meets the sea water, the electrolytes present in sea water coagulate the colloidal solution of clay resulting in its deposition with the formation of delta.

The substances that stabilise emulsions are called emulsifiers. Agar, gum and soap all are emulsifier while milk is an emulsion, not an emulsifier.

When electrophoresis, i.e., movement of particles is prevented by some suitable means, it is observed that the dispersion medium begins to move in an electric field. This phenomenon is termed electro osmosis.

Soap lather is an example of foam. Dispersion medium is liquid and dispersed phase is gas.

In the figure adsorption of coloured particle from charcoal is shown. Solution of raw sugar is filtered by animal charcoal and yellowish brown colour of raw sugar is adsorbed and filterate is colourless which gives white colour on crystallization.

Detergents are better than soaps because they are less affected by hard water, as the hydrocarbon chains in detergents do not precipitate with calcium, magnesium and other metal ions.

Smoke precipitator works on the principle of neutralization of charge on colloids.
Smoke coming out of the chimneys contain a lot of unburnt carbon particle.
Smoke is the colloidal solution of the solid particles such as carbon, arsenic, dust particles etc. These particles are injurious to health and have to be precipitated.
Carbon particle is charged particles and can not be precipitated. Thus, a metal plate of an oppositely charged particle is used for their precipitation.
This is done by the Cottrell smoke precipitator which neutralizes the charge on the carbon particles and neutralizes them.
In this way, smoke coming out of the chimneys gets free from the charged particles.

Lyophobic sols are protected due to formation of film of lyophobic sol.

The emulsion is a colloidal system consisting of immiscible liquids. Milk is an example of emulsion in which particles of liquid fat are dispersed in water. In common occurrence, however, one of the liquids is water and the other, and oily substance insoluble in it. The suspended droplets are larger than the particles of the sols. It is because of the density differences between the phases being small.

In homogeneous catalysis, only, the reactant and product are in same phase and composition is uniform throughout.

Lyophilic colloids have a unique property of protecting lyophobic colloids. When a lyophilic sol is added to the lyophobic sol, the lyophilic particles form a layer around lyophobic particles and thus protect the latter from electrolytes. Lyophilic colloids used for this purpose are called protective colloids.

Aqueous solution of soap above critical micelle concentration leads to the formation of colloidal solution. Tyndall effect is a characteristic of colloidal solution in which colloidal particles show a coloured appearance when sunlight is passes through it and seen perpendicularly.

Colloidal sols have larger surface area which provides larger sites for reactions.So,they are more effective for medical purposes.

Presence of equal and similar charges on colloidal particles provides stability to colloids as repulsive forces between charge particles having same charge prevent them from colliding when they come closer to each other.

Collodion is a colloidal sol of cellulose nitrate in ethyl alcohol.

Soaking of water by a sponge is an example of physical adsorption.
Water molecules are held to the surface of the sponge by weak van der Waals forces.

Protein water is an example of colloidal sol in which the affinity of the sol particles for the medium is due to hydrogen bonding.

When used for cleaning, soap allows insoluble particles to become soluble in water and rinsed away. The insoluble fat molecules become associated inside micelles tiny spheres formed from soap molecules with polar hydrophilic groups on outside and lipophilic pocket which shields the fat molecule from the water making it soluble.

Micelle formation is possible only above critical micelle concentration and on dilution the micelles may form electrolytes.

Action of a catalyst is highly selective in nature, i.e., a given substance can act as a catalyst only in a particular reaction and not for all the reactions. It means that a substance which acts as a catalyst in one reaction may fail to catalyse another reaction. Catalyst does not change the enthalpy of reaction.

The adhering of the molecules of gas on the surface of a solid is called adsorption. It is a surface phenomenon. It is defined as the phenomenon of accumulation of higher concentration of one substance on the surface of another than in the bulk.

River water contains charged colloidal particles of clay, sand and many other materials. Sea water is very big store house of a variety of electrolytes dissolved in it. As soon as river water comes in contact with sea water coagulate the suspended colloidal particles which ultimately settle down at the point of contact. Thus the level of the river bed rises. As a result, water adopts a different course and delta is formed in due course of time.

Adsorption and absorption when take place together, it is known as sorption.