Explanation

Torque = Force × Distance

= 15 N × 0.4 m

= 6 Nm

Explanation

The to and fro movement of a pendulum is called a vibration or oscillation.

It's a repeated back-and-forth motion about a central position.

Explanation

When a sound wave strikes a surface and bounces back into the original medium, this is called reflection.

It’s the same principle behind echoes.

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

Sodium is a metal, and metallic bonding involves positive ions in a lattice surrounded by a sea of free (delocalized) electrons.

This structure gives metals properties like electrical conductivity and malleability.

Explanation

Using the formula for parallel resistance: 1/R_eq = 1/R1 + 1/R2

1/24 = 1/40 + 1/R

Solving for R gives R = 60Ω.

Explanation

Adding two negative numbers gives a more negative result:

-14 + (-10) = -24.

Explanation

The fundus is the upper, dome-shaped portion of the stomach above the esophageal opening.

It stores undigested food and gases released during digestion.

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.