give reason why (i)tungsten is used for making filament of electric lamps; (ii) the elements of heating electrical appliaces are made up of an alloy rather than pure metal

1-Tungsten metal is selected for making filaments of  lamp bulbs because tungsten can sustain high temperatures and it has high melting point, combined with the fact that it also has high resistivity.

2-

The heating elements of electrical appliances are made of an alloy rather than pure metal because

• Alloys have higher resistivity, than constituent metals.
• They do not oxidize easily at high temperatures.