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

• The nucleus of an atom contains protons and neutrons.
• The nucleus is the central part of an atom.
• Protons have a positive charge.
• Neutrons have no electric charge.
• Electrons are found outside the nucleus
• The nucleus makes up much less than. 01% of the volume of the atom,
• But typically contains more than 99.9% of the mass of the atom.

Explanation

Water (H₂O) is a polar solvent due to its asymmetrical molecular structure.

It results in a slightly positive charge on the hydrogen atoms.

A slightly negative charge on the oxygen atom.

Explanation

• A Neutralization reaction is a specific type of reaction where an acid and a base react to form a salt and water only, with no other products.
• This reaction is characterized by the elimination of acidic and basic properties, resulting in a neutral solution.
• Example: HCl (acid) + NaOH (base) → NaCl (salt) + H2O (water)

Explanation

• Only about 2.5% (3%) of the water on Earth is freshwater, which is vital for human consumption, agriculture, and ecosystem health.
• The remaining 97.5% (97%) is saltwater, found in oceans, seas, and salt lakes.

Explanation

Global warming is primarily caused by the increasing levels of carbon dioxide (CO2) in the Earth's atmosphere, which traps heat and leads to a warming effect.

The main reason for this increase is human activities such as:

• Burning fossil fuels like coal, oil, and gas
• Deforestation and land-use changes

Explanation

The equilibrium constant, Kc, for the reaction:

N2 + O2 ⇌ 2NO is unitless (No unit).

Since the number of moles of gas is the same on both the reactant and product sides (2 moles).

The concentration terms in the equilibrium constant expression cancel out, leaving Kc without units.

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)