Explanation

Talcum powder is made from soap-stone (talc).

It is a soft mineral composed of magnesium, silicon, and oxygen.

It is widely used in cosmetics, baby powder, and industrial applications for its moisture-absorbing and friction-reducing properties.

Explanation

Measurement involves numerical values, comparison, and quantities.

But a standard is a fixed reference point, not a direct measurement itself.

Standards provide a basis for measurement rather than being a measurable trait.

Explanation

Aluminium has a valency of 3 because it loses three electrons to achieve a stable electron configuration.

Its atomic number is 13.

Its electron configuration is 2, 8, 3.

This means it donates three electrons to form Al³⁺ ions.

Explanation

To find the ratio c:a, divide the value of c by the value of a:

c:a = 20:5

Simplify the ratio by dividing both numbers by 5:

c:a = 4:1

Explanation

To convert 2/3 hours to minutes, we need to multiply 2/3 by the number of minutes in an hour, which is 60.

So, 2/3 hours = (2/3) × 60 minutes = 2 × 20 minutes = 40 minutes.

Explanation

To convert kilometers per hour (km/h) to meters per second (m/s), multiply by 1000/3600:

72 km/h = 72 × (1000/3600)

= 72 × 5/18

= 20 m/s

Explanation

Paper chromatography is a simple and widely used method for separating and analyzing mixtures of substances.

It relies on capillary action, where components of a mixture travel at different speeds on a paper strip due to differences in solubility.

Explanation

The gear system helps control speed and force by changing the torque applied to the wheels.

The wheel and axle mechanism allows smooth movement and efficient transfer of energy.

Explanation

"An" is used before words starting with a vowel sound.

"Important" begins with a vowel sound (/ɪ/), so "an" is appropriate.

"A" is used before consonant sounds.

Explanation

Forbade means to prohibit or prevent someone from doing something, which aligns with stopped.

Allowed means Permission

Managed means Handled

Facilitated means made easier