Explanation

Gears work on the principle of transmitting rotational force from one gear to another.

This helps in changing the speed, direction, or torque in a mechanical system.

Explanation

The traveler covers:

First journey: x km

Second journey: y km

Third journey: x km

Total distance = x + y + x = 2x + y

Explanation

The correct phrase is "at enmity with", used to show hostility between two parties.

"Enmity" means a state of being actively opposed or hostile to someone.

Explanation

Inertia is the property of an object to resist any change in its state of rest or uniform motion.

It is described in Newton’s First Law of Motion, also called the Law of Inertia.

Explanation

Total length of lace = 19 m 61 cm = 19.61 m

Length used = 8 m 89 cm = 8.89 m

Remaining length = Total length - Length used

Remaining length = 19.61 m - 8.89 m

Remaining length = 10.72 m

Explanation

This is the easiest test I've taken.

"Easiest" is the correct superlative form of the adjective "easy" (easy → easier → easiest).

The structure follows the rule: "the + superlative adjective" (e.g., the tallest, the smartest, the easiest).

Explanation

The bubble in a spirit level is formed by leaving an air gap inside a sealed liquid vial.

This air gap naturally moves to the highest point, helping indicate level alignment.

Explanation

"Dear" describes the noun "friend", so it is an adjective.

"Kindly" is an adverb.

"Door" is a noun.

Explanation

Antibodies are specialized proteins produced by the immune system to identify and neutralize viruses and bacteria.

They specifically bind to foreign particles (antigens) to help destroy them.

Explanation

The sum of the first n natural numbers can be calculated using the formula:

n(n + 1)/2

Here, n = 200:

Sum = 200(200 + 1)/2

= 200 * 201 / 2

= 20100