Explanation

• Urea fertilizer contains 46% nitrogen (N).
• Urea is a white crystalline solid.
• It is widely used as a fertilizer and animal feed additive.

Last verified on 31-01-2026

Explanation

• Ascorbic Acid is commonly known as Vitamin C.
• It is essential for growth, repair, and maintenance of body tissues.
• Prevents scurvy, a disease caused by Vitamin C deficiency.

Additional information:

Sources of Vitamin C (5):

1. Orange
2. Lemon
3. Guava
4. Strawberry
5. Bell pepper

Functions:

• Antioxidant
• Collagen synthesis
• Strengthens immunity

Last verified on 19-01-2026

Explanation

The slower motion of a pendulum is due to a longer period, which is related to the weaker gravitational force at higher altitudes

K2, being a very high mountain, has a significantly lower value of acceleration

Due to gravity, cities like Karachi, Murree, or Lahore result in a slower pendulum motion. 

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

If all the elements of a matrix are zero, the matrix is called a zero matrix or a null matrix. 

Explanation

• Resistivity (ρ) is a material property — it depends only on the type of material and its temperature.

• It does not depend on the length or cross-sectional area of the conductor.

Formula to clarify:

R=ρ⋅L/A​

• Here, $R$ is resistance, $L$ is length, $A$ is area, and $rho$ is resistivity.

• Length and area affect resistance, not resistivity.

Explanation

The stratospheric ozone layer is Earth's “sunscreen”  protecting living things from too much ultraviolet radiation from the sun.

Oxygen layer in the atmosphere

Ozone protects us from the harmful ultraviolet radiation of the sun.

Ozone formula: O3

The ozone layer lies approximately 15-40 kilometers (10-25 miles) above the Earth's surface, in the stratosphere.

The ozone layer is depleting: Air pollution

ND17-7-2023

Explanation

The comparative rates at which solutes move in paper chromatography depend on Rf values. 

Rf values (retention factors) represent the ratio of the distance traveled by a solute to the distance traveled by the solvent front on the paper.

Since different solutes have different polarities and affinities for the mobile and stationary phases, they will travel at different speeds, resulting in unique Rf values.

Therefore, the comparative movement of solutes is directly related to their Rf values. 

Explanation