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

The composition of dry air is:

1. Nitrogen (N2) - approximately 78.08% by volume
2. Oxygen (O2) - approximately 20.95% (21%) by volume
3. Argon (Ar) - approximately 0.93% by volume
4. Carbon Dioxide (CO2) - approximately 0.04% by volume (varies with location and time)

Explanation

Oxygen (O2) is not a greenhouse gas.

Greenhouse gases are gases in the Earth's atmosphere that absorb and emit radiation, trapping heat and contributing to the Greenhouse Effect.

The main greenhouse gases are:

• Carbon dioxide (CO2)
• Methane (CH4)
• Nitrous oxide (N2O)
• Water vapor (H2O)
• Ozone (O3)
• Chlorofluorocarbons (CFCs)
• Hydrofluorocarbons (HFCs)
• Perfluorocarbons (PFCs)

Explanation

The tropopause is the layer that separates the stratosphere and troposphere.

It's a boundary layer located at an average altitude of around 12 km (7.5 miles) above the Earth's surface, where the troposphere ends and the stratosphere begins.

Explanation

Atmospheric pressure decreases as altitude increases.

As you go higher, the air pressure decreases because there are fewer air molecules above you, exerting less pressure.

This is why aircraft pilots must adjust their altimeters to account for changes in air pressure as they ascend or descend.

Explanation

Cotton is a natural fiber that contains a very high percentage of cellulose, typically around 95%.

Cellulose is a polysaccharide (a long chain of glucose molecules) that provides strength, structure, and durability to plant cell walls.

Cotton is one of the purest forms of cellulose, making it a valuable resource for textile production.

Explanation

Fats are typically solids at ordinary room temperature (around 20-25°C or 68-77°F).

However, they can melt and become liquids when heated to a higher temperature.

Explanation

A peptide is a molecule composed of two or more amino acids linked together through amide bonds.

It is a polyamide, meaning it is a polymer of amino acids.

Peptides are smaller than proteins, which are long chains of amino acids.

Explanation

Starch is a polysaccharide, a long chain of glucose molecules linked together through glycosidic bonds.

It is a complex carbohydrate that serves as a energy storage molecule in plants.

Explanation

Aldoses are carbohydrates that contain an aldehyde group (-CHO) in their molecular structure.

The aldehyde group is a functional group that contains a carbon-oxygen double bond and a hydrogen atom.

Examples of aldoses include glucose, galactose, and ribose.