State reasons for the following:
$(a)$ Tungsten is used for making bulb filaments.
$(b)$ Copper and aluminium are generally used for electricity transmission.
$(c)$ Alloys are commonly used in electrical heating devices such as electric iron and toaster.

(N/A) Tungsten is a metal that has a very high melting point and high resistivity,which allows it to glow at high temperatures without melting,making it ideal for bulb filaments.
$(b)$ Copper and aluminium are excellent conductors of electricity because they possess very low resistivity,which minimizes energy loss during the transmission of electric current.
$(c)$ Alloys are used in electrical heating devices because their resistivity is significantly higher than that of their constituent pure metals,and they do not oxidize (burn) readily at high temperatures.