Explanation

Eukaryotic cells have a well-defined nucleus enclosed by a nuclear membrane.

Prokaryotic cells lack a nucleus — their DNA floats freely in the cytoplasm.

This is the main difference between the two.

Explanation

Explanation

• Argon (Ar) is a noble gas that is not typically associated with acid rain.

Acid rain is caused by the presence of pollutants in the air, such as:

• Sulfur dioxide (SO2)
• Nitrogen oxides (NOx)
• Oxygen (O2) plays a role in the formation of acid rain, as it reacts with SO2 and NOx to form acidic compounds.

Explanation

Diamond is a crystalline form of carbon where atoms are arranged in a regular, repeating lattice structure.

This structure gives diamond its hardness and brilliance, unlike coke or charcoal, which are amorphous.

Explanation

Diffusion is the movement of particles from high to low concentration and occurs rapidly in gases, slowly in liquids, but is negligible in solids.

In solids, particles are tightly packed and cannot move freely, so diffusion does not occur significantly.

Explanation

A covalent bond forms when two atoms share one or more pairs of electrons.

This type of bonding typically occurs between non-metal atoms to achieve stable electron configurations.

Explanation

Ionization energy is the minimum energy needed to remove one electron from a gaseous atom in its ground state.

It reflects how tightly an electron is held — higher ionization energy means stronger attraction to the nucleus.

Explanation

In this reaction, two reactants (CaO and CO₂) combine to form a single product (CaCO₃).

This is the definition of a combination (or synthesis) reaction.

Explanation

The empirical formula shows the simplest whole-number ratio of atoms in a compound (e.g., CH₂O for glucose).

It does not reflect the actual number of atoms like the molecular formula does, just their simplest ratio.

Explanation