General Science

Chlorophyll molecules contain a magnesium ion at the center of a porphyrin ring, and iron is essential for the synthesis of the chlorophyll molecule.

Individuals with blood type AB are considered universal recipients because their red blood cells have both A and B antigens, meaning they do not produce antibodies against A or B blood types.

Elasticity is the ability of a material to return to its original shape after a deforming force is removed. Among the choices, rubber is well known for its high elastic limit and ability to undergo significant reversible deformation.

Surface tension causes liquids to minimize their surface area. For a given volume, a sphere has the smallest surface area of any geometric shape.

Photosynthesis is the biological process by which green plants and some other organisms convert light energy into chemical energy stored in glucose.

Exobiology, also known as astrobiology, is the scientific study of the origin, evolution, and distribution of life in the universe, including the search for life on other planets.

Communication satellites are placed in orbit around the Earth. The exosphere is the outermost layer of the atmosphere where satellites typically orbit.

The Earth rotates 360 degrees in 24 hours. Therefore, the world is divided into 24 standard time zones, each approximately 15 degrees of longitude wide.

Crown glass is commonly used for spectacle lenses because it has good optical clarity and is relatively durable.

To prevent the glass from cracking when the temperature changes, the metal wire inserted into it must have the same coefficient of thermal expansion as the glass so they expand and contract at the same rate.

Farsightedness (hypermetropia) occurs when the eye cannot focus on near objects. A converging (convex) lens is used to help focus the light correctly onto the retina.

Resonance occurs when an external periodic force is applied to a system at its natural frequency, causing it to vibrate with large amplitude. This is a specific case of forced vibrations.

Presbyopia is a common condition in old age caused by the hardening of the eye lens and the weakening of the ciliary muscles, which results in a loss of the eye's ability to accommodate (focus on near objects).

Wood charcoal is produced by heating wood in a limited supply or absence of air (pyrolysis), which prevents the wood from burning completely into ash.

When a lift accelerates downward, the normal force exerted by the floor on the person is less than their weight, making them feel lighter (apparent weight is less than real weight).

Milk is a colloid because it consists of microscopic fat globules dispersed in a water-based liquid, and these particles do not settle out over time.

Grass is a good radiator of heat, meaning it loses heat quickly at night. This causes its temperature to drop below the dew point of the surrounding air, leading to condensation, whereas metals are generally poor radiators.

Correct Answer: Microwaves vibrate the water molecules in food, thereby generating heat

Correct Answer: Molecule