Q24 of 56 Page 85

Define the following:

(a) Amalgam


(b) Ore


(c) Mineral.

(a) An alloy of mercury with another metal is called amalgam.

(b) Mineral which contains a very high percentage of a metal and from which the metal can be economically extracted is called an ore.


(c) An element or compound which occurs naturally in the Earth’s crust is called a mineral.


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22

What is a reactivity series? Describe an activity to develop a reactivity series.

 23

How electrolytic refining of copper is carried out? Explain in detail.

 25

What is meant by corrosion? How corrosion is caused? How it can be prevented? What is the effect of corrosion on:

(a) copper?


(b) silver?

 26

(a) Make a flowchart to explain the various steps involved in the extraction of metals from ores.

(b) Give four characteristics of ionic compounds.


OR


Give reasons only:


(a) Na, K and Li are stored under oil.


(b) Pt, Au and Ag are used to make jewellery.


(c) Hydrogen gas is not evolved when metals react with nitric acid.


(d) Aluminium is a reactive metal, yet it is used to make utensils for cooking.


(e) Aqueous copper sulphate solution should not be stored in an iron container.