What will happen to the resistance of the circuit,if the current through it is doubled?

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.

$A$ heater is joined in parallel with a $60\, W$ bulb and connected to the mains. If the $60\, W$ bulb is replaced by a $100\, W$ bulb,will the rate of heat produced by the heater be more,less,or remain the same?

If three resistors of $5 \Omega$,$10 \Omega$,and $15 \Omega$ are connected in series,the equivalent resistance $R$ is equal to ........ (in $Omega$)

State Joule's law of heating.

$1 \text{ kWh} = 3.6 \times 10^6 \text{ joules}$. Is this statement true or false?