Explanation

BF₃ (Boron trifluoride) is an electron-deficient molecule because boron has only 6 valence electrons after bonding, which is less than the stable octet.

It tends to accept a lone pair from other atoms to complete its octet, making it a Lewis acid.

Explanation

Black gold is a liquid based term applied to oil or petroleum.

It comes in black color when it comes out of the ground.

It is worth a great deal of money. Petroleum is black gold.

Coal is black diamond.

Explanation

In Mendel's pea plant experiments,

When he crossed purebred pea plants with contrasting traits (like purple and white flowers),

The F1 generation offspring all exhibited the dominant trait (purple flowers in this case).

The recessive trait (white flowers) disappeared in the F1 generation but reappeared in the F2 generation when the F1 plants self-fertilized. T

his reappearance of the recessive trait in the F2 generation confirmed that the recessive allele was still present in the F1 generation, just masked by the dominant allele. 

Explanation

Cell discovered: 1665

Robert Hooke was: scientist

He belonged: UK

Explanation

Compound: a substance that is made up of more than one type of atom bonded together.

Additional Information:

Explanation

A clause is a group of words that contains both a subject and a predicate (verb).

Example: "She reads books" is a clause, where "She" is the subject, and "reads books" is the predicate.

Explanation

Refraction is the bending of light as it passes from one medium to another (e.g., air to water).

This occurs due to a change in the speed of light in different media.

Explanation

Explanation

Endangered species are those at high risk of extinction in the near future due to habitat loss, hunting, or environmental changes.

Examples include the Snow Leopard and Asian Elephant.

Explanation

Population density refers to the number of people living per unit area.

It typically measured in square kilometers or square miles.

Population density is calculated by dividing the total population of an area by the total land area.