Explanation

I have never known him for a long time.

میں اسے ایک عرصے سے کبھی نہیں جانتا تھا۔

"Have never known" is the correct present perfect tense.

It indicating that up until now, the speaker has never known the person.

Explanation

• Atoms of the same element with different numbers of neutrons are called isotopes.
• Atoms of the same element have the same number of protons and electrons but different numbers of neutrons.

Explanation

Red light rays have the lowest frequency and highest wavelength value.

Blue or violet light has the shortest wavelength.

Explanation

The following table provides the botanical names for a variety of familiar plants: 

Explanation

There are three different classes of a computer network namely:

Local Area Network (LAN) covers a small geographical area such as a room, a building or a compound;

Metropolitan Area Network (MAN) has citywide coverage

and Wide Area Network (WAN) that covers the whole globe or beyond the globe.

ND27122022

ND16-1-2023

Explanation

Defective means غلطی یا خامی ہونا ؛ صحیح طریقے سے کام نہیں کرنا

Imperfect means کامل نہیں یا غلطیاں ہیں

Explanation

Chloroform, or trichloromethane, is an organic compound with the formula CHCl₃.

It is a colorless, sweet-smelling, dense liquid that is produced on a large scale as a precursor to PTFE.

Explanation

The frequency of AC (Alternating Current) supply in Pakistan is typically 50 Hertz (Hz).

AC electricity alternates back and forth in a direction 50 times per second

Explanation

Velocity is a vector quantity. 

A vector quantity has both magnitude and direction.

Velocity, which describes the rate of change of position in a specific direction, needs both a magnitude (speed) and a direction to be fully defined. 

Vector Quantities: Velocity, momentum, torque, acceleration.

Scalar Quantities: Work, distance, speed, mass.

Explanation

Molten NaCl conducts electricity.

Because it contains free-moving Na⁺ and Cl⁻ ions.