Explanation

Alkaline earth metals: These elements have two valence electrons in their outermost s orbital.

3rd period: In the third period, the outermost shell is the 3rd shell. 

Therefore, the electronic configuration of an alkaline earth metal in the 3rd period is [Ne] 3s².

Explanation

Crystal lattices are classified into seven crystal systems based on their unit cell geometry.

These include:

1. Cubic
2. Tetragonal
3. Orthorhombic
4. Monoclinic
5. Triclinic
6. Hexagonal
7. Rhombohedral (Trigonal)

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

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

Polyethene, also known as polyethylene, is a type of plastic.

It is a thermoplastic polymer made from ethylene monomers.

It is commonly used in packaging, plastic bags, and containers.

Explanation

To calculate the molarity, we need to calculate the number of moles of sodium chloride (NaCl) dissolved in 500 cm³ (or 0.5 L) of solution.

Molar mass of NaCl = 58.44 g/mol

Number of moles = mass / molar mass = 40 g / 58.44 g/mol ≈ 0.684 mol

Molarity = number of moles / volume (in liters) = 0.684 mol / 0.5 L ≈ 1.368 M

Rounded to one decimal place, this is approximately 1.4M.

Explanation

• Plasma is a state of matter where atoms or molecules are ionized, meaning they have lost or gained electrons, resulting in a collection of charged particles.
• Plasma is often referred to as the fourth state of matter.
• It is the lightest form of matter, as the particles are highly energetic and widely spaced.

Explanation

• Vapor pressure is the pressure exerted by the vapor of a liquid in equilibrium with its solid or liquid phase.
• As temperature increases, the molecules of a liquid gain kinetic energy and move more rapidly.
• Increasing the number of molecules that escape into the vapor phase, thereby increasing the vapor pressure.

Explanation

• The nucleon number (mass number) of Potassium is 39, and the atomic number (number of protons) is 19.
• To find the number of neutrons, subtract the number of protons from the nucleon number:
• 39 (nucleon number) - 19 (proton number) = 20
• So, the number of neutrons in Potassium-39 is 20.

Explanation

Chromatography is one of the latest techniques, which is used to separate the colored components of a mixture.

Ink is a mixture of several dyes

therefore we can separate those colors from one another using chromatography.

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ND20-1-2023