Explanation

The order of speed of sound in different mediums, from fastest to slowest, is:

• Solid (approximately 3000-6000 m/s)
• Liquid (approximately 1000-3000 m/s)
• Gas (approximately 300-400 m/s)

Explanation

Kerosene oil is used as jet fuel, commonly known as Jet-A or Jet-A1.

It has a high energy density and good combustion properties suitable for aircraft engines.

Explanation

The carboxylate end of a soap molecule (-COO-) is hydrophilic (water-loving), meaning it is attracted to water.

This end of the molecule is negatively charged and is able to form hydrogen bonds with water molecules, which are polar and also have a slightly positive charge.

Explanation

Sedatives are drugs that slow down normal brain functioning, leading to a calming or tranquilizing effect.

They can reduce anxiety, stress, and even induce sleep.

Examples of sedatives include benzodiazepines (e.g., Xanax, Valium), barbiturates, and certain antidepressants.

Explanation

Restriction enzymes are naturally occurring enzymes used by bacteria as a defense mechanism to protect themselves from viral infections.

These enzymes recognize specific DNA sequences and cut the DNA at those sites, preventing viral replication.

This defense strategy is known as the restriction-modification system.

Explanation

Each stoma (singular of stomata) is formed by two guard cells, which are specialized cells that surround the stoma and control its opening and closing.

The guard cells swell or shrink to adjust the aperture of the stoma, regulating gas exchange and transpiration in plants.

Explanation

Long-sightedness is also known as hyperopia.

It is a vision defect where the image is formed beyond the retina, rather than directly on it.

This occurs when the eyeball is too short or the cornea is too flat, causing light to focus at a point behind the retina.

As a result, close objects appear blurry, while distant objects may remain clear.

Explanation

An echo is caused by the reflection of sound waves off a surface or object.

When sound waves reach a surface, some of the energy is reflected back, creating an echo.

This reflected sound wave then travels back to the listener, arriving later than the original sound, causing the echo effect.

Explanation

Ammonia (NH3) is not a fraction of crude oil.

Crude oil is a mixture of various hydrocarbons, which are separated into different fractions based on their boiling points and properties.

The main fractions of crude oil are:

• Refinery gas
• Liquefied petroleum gas (LPG)
• Naphtha
• Gasoline
• Kerosene
• Diesel fuel
• Fuel oil
• Lubricating oils
• Paraffin wax
• Petroleum coke (also known as petcoke)

Explanation

The tropopause is the layer that separates the stratosphere and troposphere.

It's a boundary layer located at an average altitude of around 12 km (7.5 miles) above the Earth's surface, where the troposphere ends and the stratosphere begins.