Everyday Science

The seasons change because the Earth revolves around the Sun, causing different parts of the Earth to receive varying amounts of sunlight throughout the year. This revolution, combined with the tilt of Earth's axis, leads to seasonal changes.

Phobos is one of the two natural satellites (moons) of Mars, making Mars the correct answer. The other options do not have Phobos as a satellite.

Freon and ammonia are commonly used refrigerants in domestic refrigerators due to their suitable thermodynamic properties. Neon, spirit, and methane are not used as refrigerants in household refrigeration systems.

Wood is an insulator and conducts electricity very poorly compared to copper, iron, and water. Copper and iron are metals and good conductors, while water can conduct electricity due to dissolved ions.

18 carat gold means 18 parts gold out of 24 parts total, so the ratio of pure gold is 18/24 = 0.75.

Wood is primarily used as the main raw material in the manufacture of paper, as it contains cellulose fibers essential for paper production. Paint, gunpowder, and ink do not primarily rely on wood as their raw material.

Children aged 1 to 3 years typically require between about 1,000 and 1,400 kilocalories per day to meet their energy needs, depending on their activity level and growth. The option of 300 kilocalories is far too low, and 600 or 900 kilocalories are also below typical requirements. The best estimate from authoritative sources such as CDC and nutrition guidelines is around 1,200 kilocalories per day for this age group.

Water vapor condenses into tiny droplets when the air cools to its dew point, leading to cloud formation. This process happens because the air becomes saturated and cannot hold all the moisture as vapor.

Water is known as a universal solvent primarily because it dissolves many substances involved in biochemical reactions, such as those in living organisms. While it can dissolve substances in chemical reactions as well, its role as a universal solvent is most significant in biochemical contexts.

Most drugs are primarily excreted through the kidneys via urine. While some drugs can be excreted through other routes like the lungs or skin, the kidney is the main organ responsible for drug excretion.