Explanation

• Alternating Current (AC) is the flow of electric charge that periodically changes direction.
• This type of current is commonly used in power distribution systems and household electrical outlets.

Explanation

• Atmospheric pressure is a scalar quantity that acts equally in all directions, pressing on surfaces from all sides.
• This is why a balloon expands in all directions when inflated, and why a submarine is squeezed from all sides by the surrounding water pressure.

Explanation

• Citric acid is a natural preservative found in many fruits, particularly in citrus fruits like lemons, oranges, and grapefruits.
• It's responsible for their sour taste and is also used as a food additive.
• Other fruits like mangoes, grapes, and strawberries also contain citric acid, although in smaller amounts.
• The presence of citric acid gives these fruits their characteristic sour taste.

Explanation

• The poisonous gas which is the main byproduct of motor vehicles with an irritating smell is sulfur dioxide (SO₂).
• Sulfur dioxide is produced by the combustion of fossil fuels containing sulfur and contributes to air pollution and respiratory problems.

Explanation

• The electrons that have been knocked out of the outermost shell of an atom are free electrons, which are able to move freely and conduct electricity.

Explanation

• Carbon dating is used to estimate the age of fossils.
• Those that are less than 60,000 years old.
• It is composed of organic materials like wood or leather.

Explanation

• Chlorophyll is the green pigment found in chloroplasts.
• It responsible for absorbing light energy and playing a central role in photosynthesis.

Explanation

• In both microscopes and human eyes, the iris (or diaphragm) controls the amount of light that enters the instrument or eye.
• In microscopes, it regulates the amount of light that reaches the objective lens.
• While in human eyes, it regulates the amount of light that enters the pupil.

Explanation

• When you run a plastic comb through your dry and non-oily hair, the comb becomes statically charged.
• This static charge causes the comb to attract small, light objects like bits of paper.
• When you hold the comb above the paper, the paper is attracted to the comb due to the electrostatic force.

Explanation

• Wear and Tear is not an advantage of friction.
• It's a disadvantage, as friction causes wear and tear on surfaces.

Advantages of Friction:

• Walking: Friction between the soles of our shoes and the ground allows us to walk without slipping.
• Braking: Friction between the brake pads and the wheels allows vehicles to slow down and stop.
• Securing knots: Friction between the fibers of a rope helps keep knots tight and secure.
• Fasteners: Friction between threads in screws and bolts helps keep them in place and secure