Identify the dispersed phase and dispersing medium in the following colloids. (a) Fog (b) Cheese (c) Coloured gemstone
(a) Fog-liquid, gas (b) Cheese-liquid, solid (c) Coloured gemstone--solid, solid
Is water an element or a compound? Give reason in support of your statement.
Water is a compound because of the following reasons: (i) It is composed of two different elements, hydrogen and oxygen which cannot be separated by physical methods. They can be…
Which of the following are not compounds Chlorine gas (b) Potassium chloride (c) Iron (d) Iron sulphide (e) Aluminium (f) Iodine (g) Carbon (h) Carbon monoxide (i) Sulphur powder.
Chlorine gas, iron, aluminium, iodine, carbon, sulphur powder.
Give two points of differences between an element and a compound
Element Compound 1. An element is made up of same kind of atoms. A compound is obtained from different kinds of atoms. 2. An element cannot be split by physical…
Classify the following as physical or chemical properties: (a) The composition of a sample of steel is 98% iron, 1.5% carbon and 0.5% other elements. (b) Zinc dissolves in hydrochloric acid with the evolution of hydrogen gas. (c) Metallic sodium is soft enough to be cut with a knife. (d) Most metal oxides form alkalis on interacting with water.
Physical properties-(a) and (c) Chemical properties-(b) and (d)
Rain water stored in a tank contains sand grains, unfiltrable clay particles, calcium carbonate, salt, pieces of paper and some air bubbles. Select from amongst these one example each of a solvent, a solute, a colloid and a suspension.
Solvent – water Solute – salt Colloid - air bubbles Suspension -clay particles
Define chromatography and give its one application.
Chromatography is a technique used for the separation of a mixture of solutes brought about by distribution of dissolved material between two immiscible phases, one of which is mobile phase…
While diluting a solution of salt in water, a student by mistake added acetone (boiling point 560C) What technique can be employed to get back the acetone? Justify your choice.
Distillation is used to get back acetone. We know that boiling point of water is 100°C and since acetone is more volatile it will separate out first.
What do you understand by the term distillation? Give its one application.
Distillation is a process of boiling a liquid and then condensing the vapour obtained into a liquid. This process is used to obtain wines from the sugarcane juice.
Smoke and fog both are aerosols. In what way are they different?
Both fog and smoke have gas as the dispersion medium. The only difference is that the dispersed phase in fog is liquid and in smoke it is a solid.