Explanation

The stratosphere is the second layer of Earth's atmosphere as you go upwards, lying above the troposphere and below the mesosphere.

The layers of the Earth's atmosphere, in order from the surface, are:

1. Troposphere (up to about 12 km/7.5 miles)
2. Stratosphere (up to about 50 km/31 miles)
3. Mesosphere (up to about 85 km/53 miles)
4. Thermosphere (up to about 600 km/373 miles)

Explanation

Ozone (O3) is a gas found in the stratosphere.

A stratosphere layer of the atmosphere that extends from about 12 to 50 kilometers (7.5 to 31 miles) above the Earth's surface.

The ozone layer, also known as the ozonosphere.

Explanation

• If the pH value is greater than 7, the solution is basic (also known as alkaline).
• This means that the concentration of hydroxide ions (OH-) is higher than the concentration of hydrogen ions (H+).

Key Points:

• pH < 7: Acidic
• pH = 7: Neutral
• pH > 7: Basic (or alkaline)

Explanation

Ammonia (NH3) is not a fraction of crude oil.

Crude oil is a mixture of various hydrocarbons, which are separated into different fractions based on their boiling points and properties.

The main fractions of crude oil are:

• Refinery gas
• Liquefied petroleum gas (LPG)
• Naphtha
• Gasoline
• Kerosene
• Diesel fuel
• Fuel oil
• Lubricating oils
• Paraffin wax
• Petroleum coke (also known as petcoke)

Explanation

Kerosene oil is used as jet fuel, commonly known as Jet-A or Jet-A1.

It has a high energy density and good combustion properties suitable for aircraft engines.

Explanation

Harvesting is the most important step in the preparation of sugar from sugarcane or sugar beets.

Sugarcane is typically harvested by hand or by machine, and sugar beets are harvested by machine.

The quality of the harvest affects the quality of the sugar produced.

Explanation

Abrasives are substances that wear away or remove material through friction or rubbing.

Examples of abrasives include:

Water insoluble minerals like:

• Silica (sand)
• Alumina (aluminum oxide)
• Calcium carbonate (limestone)
• Diamond

Explanation

A centrifuge is a machine that uses centrifugal force to separate particles of different densities or sizes from a mixture.

It is commonly used to separate:

• Liquids from solids (e.g., mud, sludge)
• Heavy particles from lighter particles (e.g., sedimentation)
• Immiscible liquids (e.g., oil and water)

Explanation

Citric acid is a natural preservative and flavoring agent that is commonly used in foods and beverages to add a sour taste.

It is particularly useful in cold drinks, such as:

• Soft drinks (e.g., lemon-lime soda)
• Fruit juices (e.g., orange, grapefruit)
• Sports drinks
• Energy drinks

Explanation

Potassium hydroxide (KOH) is used to make soft soaps, which are typically more soluble and have a lower melting point than soaps made with sodium hydroxide (NaOH).

Soft soaps are often used in liquid soaps, shampoos, and body washes.