Explanation

In a longitudinal wave, particles of the medium move parallel to the direction of wave propagation.

Sound waves in air are a common example of longitudinal waves.

Explanation

Hepatitis C is a liver infection caused by the hepatitis C virus. 

Hepatitis C is often described as “acute,” meaning a new infection, or “chronic,” meaning long-term infection.

Explanation

Oxyacetylene flame is used in welding and cutting metals due to its high temperature.

It provides a flame temperature of about 3200°C, making it suitable for industrial applications.

Explanation

Explanation

• Exposure to sunlight triggers the production of vitamin D in the skin.
• Specifically, ultraviolet B (UVB) rays from the sun interact with a compound called 7-dehydrocholesterol, converting it into vitamin D3 (cholecalciferol).
• Vitamin D is essential for calcium absorption, bone health, and immune system regulation.

Explanation

Calcium oxalate is the most common compound found in kidney stones.

It forms when excess calcium and oxalate in the urine combine, creating hard crystals that can grow into stones.

Explanation

موسم بدلتا ہے کیونکہ زمین سورج کے گرد گھوم رہی ہے۔

Earth's tilted axis causes the seasons. Throughout the year, different parts of Earth receive the Sun's most direct rays.

So, when the North Pole tilts toward the Sun, it's summer in the Northern Hemisphere. And when the South Pole tilts toward the Sun, it's winter in the Northern Hemisphere. 

Explanation

Explanation

Sucrose is also known as Table sugar.

Sucrose is a type of common sugar.

It is a disaccharide, a molecule which consists of two monosaccharides: glucose and fructose.

Explanation

Mirage is an example of:

• refraction of light
• total internal reflection

Example

When the reflected light ray reaches our eyes, it appears as coming from the sky or tree.

This inverted image creates an optical illusion of the presence of water or the presence of islands etc.