Explanation

The retention factor (Rf) in chromatography is a unitless value

Because it is calculated as a ratio of two distances (distance traveled by the solute and distance traveled by the solvent), the units of length cancel out. 

Explanation

A body in equilibrium means all the forces acting on it are balanced, resulting in no net force.

Since acceleration is directly related to the net force (F = ma), if the net force is zero, then the acceleration must also be zero. 

Explanation

Ohm's law is not applicable to Semiconductors, as the relationship between voltage and current does not remain constant in these devices.

Semiconductors have a non-linear current-voltage characteristic, making Ohm's law inapplicable.

Explanation

When two capacitors of equal capacitance (C) are connected in series, the equivalent capacitance (Ceq) is half the value of one capacitor:

Ceq = (C × C) / (C + C) = (C × C) / 2C = C/2

In this case, C = 8 µF, so:

Ceq = 8 µF / 2 = 4 µF

Therefore, the equivalent capacitance of the two 8 µF capacitors connected in series is 4 µF.

Explanation

Sound travels faster in solids than in gases because the molecules in a solid are packed more tightly together, allowing the energy to be transferred more efficiently.

In contrast, in a gas, the molecules are spaced farther apart and are free to move randomly, making it harder for the sound wave to propagate.

Explanation

When a gas changes into a liquid, the molecules:

• Move closer together (their distance decreases)
• Lose kinetic energy (they slow down)

Explanation

If a spring stretches easily, it means that it requires less force to stretch it a certain distance.

This is indicative of a spring with a small spring constant (k).

The spring constant is a measure of a spring's stiffness.

A smaller value means the spring is less stiff and more easily deformed.

Explanation

• SUPARCO (Space and Upper Atmosphere Research Commission) is the space agency of Pakistan.
• It was established in 1961.
• SUPARCO is responsible for the national space program of Pakistan and has developed the capacity for a national satellite program.

Explanation

Conduction is heat transfer through stationary matter by physical contact. 

Convection is the heat transfer by the macroscopic movement of a fluid.

Heat transfer by radiation occurs when microwaves, infrared radiation, visible light, or another form of electromagnetic radiation is emitted or absorbed.

Explanation

The heavily doped region of a transistor is called the emitter.

The emitter's heavy doping ensures it injects a large number of charge carriers (electrons in NPN transistors, holes in PNP transistors) into the base region, which is crucial for the transistor's operation.