b) Spyware

Since the protons are positively charged particles, they will repal each other. To bring them nearer, work has to be done against the force of repulsion and this will be stored up in the system as potential energy. So the potential energy of the system will increase.

The gravitational force on the comet due to the sun is not normal to the comet's velocity in general. Yet the work done by the gravitational force over every complete orbit of the comet is zero. Why? The gravitational force is conservative force.

The meteorite moves under the force of gravity therefore , its momentum goes on changing . But total momentum of meteorite and earth is always conserved

The energy of the bus has to go somewhere, and the momentum too, as they are independently conserved.

There is no external force as car is having constant speed

The energy is dissipated in the form of heat. The heat energy so produced is not available for work.