Explanation

The bottom of the stratosphere is around 10 km (6.2 miles or about 33,000 feet) above the ground at middle latitudes.

The top of the stratosphere occurs at an altitude of 50 km (31 miles).

Explanation

Amphoteric substances are those that can react with both acids and bases.

They can donate or accept protons (H+ ions), depending on the conditions.

Examples of amphoteric substances include water (H2O), amino acids, and certain metals like zinc and aluminum.

Explanation

Nitrification is the process by which nitrogenous compounds in living organisms, such as ammonia (NH3), are converted into nitrates (NO3-) by microorganisms like bacteria.

This process occurs in soil, water, and the gut of animals, and is an essential step in the nitrogen cycle.

Explanation

Ligaments are bands of tough, fibrous, connective tissue that connect bones to each other at joints, providing stability and support.

They are essential for maintaining joint integrity and preventing excessive movement.

Explanation

The numerical value of G (the gravitational constant) remains constant everywhere in the universe, regardless of the location, time, or conditions.

G is a fundamental constant of nature that describes the strength of gravitational attraction between objects.

Explanation

According to Newton's law of universal gravitation, the force of gravity (F) is proportional to:

• The product of the two masses (m1 and m2): F ∝ m1 m2
• The inverse square of the distance (r) between the centers of the two objects: F ∝ 1/r^2

Explanation

A 10% (w/w) sugar solution means that 10 grams of sugar (the solute) is dissolved in 90 grams of water (the solvent), making a total of 100 grams of solution.

The percentage is calculated as:

(10 g sugar / 100 g total) × 100% = 10% (w/w)

So, 10 grams of sugar is dissolved in 90 grams of water.

Explanation

A diatomic molecule is a molecule composed of two atoms, either of the same element (homogeneous) or different elements (heterogeneous).

Examples of diatomic molecules include:

• Hydrogen (H2)
• Oxygen (O2)
• Nitrogen (N2)

Explanation

• Photolysis is the process by which water (H2O) is split into hydrogen ions (H+), electrons, and oxygen (O2) in the presence of light.
• This process occurs in the thylakoid membranes of chloroplasts during photosynthesis and is driven by light energy.

Explanation

• Meiosis is a type of cell division that occurs in germ cells (reproductive cells) to produce gametes (sperm or egg cells).
• It does not produce new somatic cells (non-reproductive cells).