Correct answer only ! which represents the smallest number?

Feel like I'm doing your homework or test for you lol.

The smallest value is 3.8 * 10^-18

Why?

Because you are moving the decimal point 18 times to the left of 3.8, therefore it is an EXTREMELY small number.

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

                                              ⇒      

here   k is the proportionality constant whose value is 1.

                                                            [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.