Explanation

A hydrophone is an instrument designed to detect and record sound underwater.

It's essentially the underwater equivalent of a microphone and is commonly used in:

• Marine biology (e.g., studying whale calls or dolphin clicks)

• Submarine and naval operations (e.g., detecting other submarines or ships)

• Environmental monitoring (e.g., measuring underwater noise pollution)

• Underwater research (e.g., studying seismic activity or underwater volcanic eruptions)

Explanation

The Heavy Water Plant at Talcher and the Fertilizer Plant at Paradeep are both located in the state of Odisha (formerly Orissa), India.

Talcher is known for its heavy water production used in nuclear reactors.

While Paradeep is a major industrial and port city with fertilizer and petrochemical industries.

Explanation

"Expedition" refers to a journey or trip, often with a planned purpose, like survival.

"The expedition leaders made careful plans as to how much food and what kinds of clothing the team would need to survive" is the appropriate choice.

Explanation

Thomas Edison is often credited as a key figure in the development of motion picture technology due to his invention of the Kinetoscope, an early motion picture exhibition device.

His contributions in the late 19th century laid the groundwork for the commercial motion picture industry, making him a pivotal figure in film history.

Explanation

"Did not stop" is the correct past tense form of the verb "stop".

"Covered" is the simple past form that matches the sequence of past events.

This sentence follows the structure of two completed actions in the past.

Correct sentence:

"Ali did not stop studying until he covered all the exam topics."

Explanation

Lahore is the most crowded city in Pakistan."

• "In" is used to show location within a country, city, or region.

• We say "in Pakistan" to indicate that Lahore is within the country.

So, "in" is the correct preposition here.

Explanation

Given:

• 16 machines finish the work in 4 days

• Now we want to know how many days will take 8 machines for the same work

Concept:

More machines → Less time
Fewer machines → More time
This is an inverse proportion relationship.

So,

$$text{Days} propto frac{1}{text{Machines}}$$ $$text{New Days} = 4 times frac{16}{8} = 4 times 2 = 8 text{ days}$$

Explanation

The sentence needs a past participle form of the verb "repair" after the preposition "have,"

This indicates that the electrician should have the switch repaired.

The structure "have someone past participle something" means that someone else should get something done by someone else.

Explanation

The sentence has an independent clause ("Rick prepared the food") and a dependent clause ("that they had ordered") connected by a relative pronoun ("that").

A complex sentence contains both independent and dependent clauses.

Explanation

The India-Nepal-China corridor was a concept proposed by China under its Belt and Road Initiative (BRI) to enhance regional connectivity.

It aimed to link the three countries for trade and infrastructure development, though it faced reservations from India.