Explanation

Reflecting telescopes primarily use concave mirrors to collect and focus light.

While some designs might incorporate a plane mirror for specific purposes, the key component is the concave mirror.

In more complex designs like the Cassegrain telescope, a secondary convex mirror is added to further focus the light onto the eyepiece. 

Explanation

When white light shines on a green leaf, the chlorophyll pigment in the leaf absorbs most wavelengths of light except for green.

The green light is reflected, making the leaf appear green to our eyes. 

Explanation

An atom is made up of smaller particles called subatomic particles, which include protons, neutrons, and electrons.

Protons and neutrons are found in the atom's central nucleus, while electrons orbit the nucleus. 

Protons: have a positive electrical charge and are located in the nucleus. 

Neutrons: have no electrical charge (they are neutral) and are also found in the nucleus. 

Electrons: have a negative electrical charge and orbit the nucleus in an electron cloud. 

Explanation

Quarks are the smallest known particles in the universe.

They are the building blocks of protons and neutrons, which make up atomic nuclei.

They were discovered in the 1960s. 

They are considered the most fundamental units of matter.

Explanation

To kill bacteria in a filtration plant, chlorine is used.

This process, known as chlorination, is one of the most common methods of water disinfection. 

Chlorine is effective because it:

Kills or inactivates disease-causing microorganisms, such as bacteria, viruses, and parasites.

It is relatively inexpensive and easy to apply.

While other methods like ozone and ultraviolet (UV) light are also used for disinfection

Explanation

Bacillus refers to rod-shaped bacteria.

Coccus are spherical.

Spirillum are spiral-shaped.

Explanation

• On Earth, surface water covers 70% area.
• 70-71 percent of the Earth's surface is water-covered.
• The oceans hold about 96.5 percent of all Earth's water.
• ***
• This includes oceans, rivers, lakes, glaciers, and groundwater.
  

Explanation

Explanation

Helical gear, more commonly known as double helical or herringbone gears.

This design cancels out the axial thrust forces that typically put a load on the shaft. 

Explanation

Frictional force is directly proportional to the normal force, which for a horizontal surface is equal to the weight of the body.  

So, if the weight increases, the friction also increases.

- Friction ∝ Normal Force (Weight on horizontal surface)