The SI unit of electric charge is known as Columb, which is named after Charles Augustin de Columb-a renowned French physicist.

Conductor is an object through which electricity can pass in one or more direction. Aluminum, Silicon, Graphite, Copper, Gold etc. are the widely used examples of conductors.

Velocity is a vector quantity because it has both magnitude and direction, unlike scalar quantities like mass, speed, and distance.

 According to International System of Units (SI), Tesla (T) is the unit of magnetic flux density (also called magnetic strength) where one tesla is equal to one weber per square meter.

A simple machine is a mechanical device that changes the state of condition or force with least external (human) effort. So, only Wheel among the above options can hardly propel itself without axle.

Convection results in the tendency to expand when heated-Water, Air etc.

Rocket Engine works based on third rule of Sir Isaac Newton-"For every action there is an equal and opposite reaction."

First rule-An object will not change its motion unless any external force acts on it. Second rule-Heavier objects need a larger force to move them. third rule-For every action there is an equal and opposite reaction.

As the train is running, the ball with the boy is also running in a same horizontal velocity. Hence the ball will come back to the hand of the boy.

Due to higher center of gravity and limited suspension a car overturn quickly on a curved road. In other way, when a car overturn quickly on a curved road, its lower part moves towards the center very quickly, but its upper part doesn't follow accordingly.