Explanation

Vertical columns in the periodic table are called groups.

Horizontal rows are called periods.

Explanation

A moving car possesses kinetic energy due to its motion.

Kinetic energy depends on the mass and speed of the object.

Explanation

Explanation

The nucleus is the dense center of an atom, containing protons (positively charged) and neutrons (neutral).

Electrons orbit around the nucleus in electron shells.

Explanation

Metallic oxides react with water to form bases, as shown in the example:

Na₂O + H₂O → 2NaOH

This reaction demonstrates the basic nature of metallic oxides, forming a strong base (sodium hydroxide, NaOH) when reacting with water.

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

The conjugate acid of water (H₂O) is H₃O⁺ (hydronium ion).

When water acts as a base, it accepts a proton (H⁺) and forms H₃O⁺.

Explanation

In electronic transitions, a direct transition from 2s to 1s is forbidden.

Due to quantum mechanical selection rules.

Explanation

Cadmium is not a radioactive element.

It is a metal used in batteries and coatings.

Whereas Uranium and Plutonium are radioactive.

They used as nuclear fuels.

Explanation