Explain inertia, Newton's First Law, the SI unit of force and Newton's Third Law with examples.

A passenger leaning forward when a bus suddenly brakes is an example of inertia. The passenger's body tends to continue moving forward due to its inertia, even though the bus is decelerating. Newton's First Law of Motion is also known as the Law of Inertia.

A) Second Law - Incorrect.
B) Third Law - Incorrect.
C) First Law - Correct.
D) Law of Gravitation - Incorrect.

The correct option is C.

The SI unit of force is the Newton (N). According to Newton's Second Law ($F=ma$), a Newton can also be expressed in terms of fundamental SI units as kilograms times meters per second squared.

A) $\text{kg m/s}$ - This is the unit for momentum. Incorrect.
B) Newton ($\text{kg m/s}^2$) - Correct.
C) Joule - This is the unit for energy or work. Incorrect.
D) Pascal - This is the unit for pressure. Incorrect.

The correct option is B.

A rocket moves forward by expelling gas backwards. This is an example of an action-reaction pair: the rocket exerts a force on the gas (action), and the gas exerts an equal and opposite force on the rocket (reaction), propelling it forward. This phenomenon is described by Newton's Third Law of Motion.

A) First Law - Incorrect.
B) Second Law - Incorrect.
C) Third Law - Correct.
D) Law of universal gravitation - Incorrect.

The correct option is C.