Explanation

The invention and advancement of the vacuum or electron tube marked the beginning of the Electronic Era in the early 20th century.

These tubes were used in early radios, televisions, and computers.

Explanation

Cyber bullying often causes emotional distress, like frustration, fear, anxiety, and low self-esteem.

Happiness is not one of the emotions typically experienced by victims.

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

Explanation

Sulphur powder is commonly found as a bright yellow solid.

It is non-metallic.

It is used in medicines, fertilizers, and chemicals.

Explanation

Let's calculate the number of protons, neutrons, and electrons for both atoms:

³¹₁₅P (Phosphorus)

•     Protons: 15
•     Neutrons: 31 - 15 = 16
•     Electrons (neutral atom): 15

³²₁₆S (Sulfur)

•     Protons: 16
•     Neutrons: 32 - 16 = 16
•     Electrons (neutral atom): 16

Both atoms have the same number of neutrons (16).

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 decomposition reaction involves a single compound breaking down into simpler substances.

AB → A + B is the correct format for decomposition.

Explanation

Explanation

To find the harmonic that is two octaves higher in pitch than the fundamental, we need to consider the frequency multiplication.

One octave higher = 2 × fundamental frequency

Two octaves higher = 2 × 2 × fundamental frequency = 4 × fundamental frequency

The fourth harmonic has a frequency four times the fundamental frequency, which corresponds to two octaves higher.