Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal ?

What are the factors on which resistance of a conductor depends? Why are coils of electric toasters and electric irons made of an alloy rather than that of a pure metal?

Explain the following : (a) Why is tungsten used almost axclusively for filament of incandescent lamp ? (b) Why are the conductors of electric heating devices, such as toaster and electric irons, made of an alloy rather than a pure metal ? ( c) Why is the series arrangement not used for domestic circuits ? (d) How does the resistance of a wire vary with its cross-sectional area ? (e ) Why are copper and aluminimum wires usually employed for electricity transmission.

What is the difference between the terms overloading and short-circuiting? Why are coils of electric heaters made of an alloy rather than a pure metal?