Which of the following sets consists of S.I. units only?

here are the solutions to questions 1, 2, 3, 4, and 5:

Question 1:
B) The set that consists of S.I. units only is kg, m, s.

• Kilogram (kg) is the S.I. unit for mass.
• Meter (m) is the S.I. unit for length.
• Second (s) is the S.I. unit for time. Other options contain non-S.I. units or prefixes that make them not base S.I. units (e.g., gram, millimeter, hour, milligram, kilometer, centimeter).

Question 2:
A) The statement that is incorrect about frictional force is that it depends on the area of the surfaces in contact.

• For solid surfaces, the force of friction is generally independent of the apparent area of contact, as long as the normal force remains constant.

Question 3:
B) An example of a body that is not accelerating is a car descending a hill.

• If the car is descending the hill at a constant velocity, then its acceleration is zero.
• A bicycle slowing down (A), a falling mango (C), and a plane taking off (D) all involve a change in speed, hence acceleration.
• A satellite orbiting the sun (E) is constantly changing direction, which means it has centripetal acceleration.

Question 4:
D) The quantity that is a scalar is Temperature.

• Scalar quantities have only magnitude (e.g., temperature, mass, speed).
• Vector quantities have both magnitude and direction (e.g., displacement, impulse, momentum, velocity).

Question 5:
E) An object immersed in water experiences weight loss because of the upthrust on it.

• According to Archimedes' principle, a fluid exerts an upward buoyant force (upthrust) on an immersed object, which opposes the object's weight, making it feel lighter.