How many joules are there in one kilowatt-hour?

$(a)$ How is the direction of electric current related to the direction of flow of electrons in a wire?
$(b)$ Calculate the current in a circuit,if $500 \, C$ of charge passes through it in $10$ minutes.

How much work is done in moving a charge of $2 \ C$ from a point at $118 \ V$ to a point at $128 \ V$ (in $J$)?

Describe the nature of the $V-I$ graph for a nichrome wire. ($V =$ Potential difference,$I =$ Current)
$A$ metallic wire of $625 \, mm$ length offers a $4 \, \Omega$ resistance. If the resistivity of the metal is $4.8 \times 10^{-7} \, \Omega \cdot m$,calculate the cross-sectional area of the wire.

$A$ wire of resistance $5 \, \Omega$ is bent in the form of a closed circle. What is the resistance between two points at the ends of any diameter of the circle?

What is the symbol used to denote the unit of resistance,ohm?