Question

(a) What is the action on litmus of:
(i) Dry ammonia gas
(ii) Solution of ammonia gas in water
(b) State the observations you would make on adding ammonium hydroxide to aqueous solutions of:
(i) Ferrous sulphate
(ii) Aluminium chloride
OR
Explain the following terms by giving one example of each.
(i) Mineral
(ii) Ore
(iii) Gangue

Answer 1

(I) Mineral...........
Minerals are substances that are formed naturally in the Earth. Minerals are usually solid, inorganic, have a crystal structure, and form naturally by geological processes. The study of minerals is called mineralogy. Amineral can be made of single chemical element or more usually a compound.
Example-aluminium, magnesium, iron, calcium, sodium, and potassium. Some important rock-forming silicates include the feldspars, quartz, olivines, pyroxenes, amphiboles, garnets, and micas.

(ii) Ore..........
A naturally occurring mineral or rock from which a valuable or useful substance, especially a metal, can be extracted at a reasonable cost.
Example- cinnabar (HgS), an ore of mercury, sphalerite (ZnS), an ore of zinc, orcassiterite (SnO2), an ore of tin (Mineral). 

(iii) Gangue
Gangue is valueless mineral associated with avaluable mineral that can economically be utilized.
Example- An example of gangue is the rock surrounding a deposit of gold.

Answer 2

Mineral : element or compound accuring naturally are called minerals

Ore: minerals from which metals can be extracted

Gangue: waste practicals removed from ore