Explanation

• The scientist who first discovered that the earth revolves around the sun was Copernicus.
• Earth's Rotational Theory:
  • Rotation can be defined as the spin of Earth on its own axis from west to east direction.
  • It must also be noted that the speed of rotation of the earth is not constant throughout latitudes.
    
  • It differs at different latitudes.

Explanation

Geothermal, Solar, and Hydropower all come from naturally replenished sources.

These energies are renewable because they do not deplete with use and are environmentally friendly.

Renewable sources of energy include:

• Solar energy
• Wind energy
• Hydropower
• Geothermal energy
• Biomass

Explanation

• The most abundant component in Earth's atmosphere is nitrogen, making up about 78% of the air.
• The second most abundant gas is oxygen, which makes up about 21% of the air.
• Hydrogen and carbon dioxide are both present in the air, but in much smaller amounts than nitrogen and oxygen.

Explanation

Explanation

Cooking is difficult in the mountains primarily due to low atmospheric pressure, which affects the boiling point of water. 

Decreased Pressure at High Altitude:

As altitude increases, the atmospheric pressure decreases because there is less air pushing down from above.

Lower Boiling Point:

Water boils when its vapor pressure equals the surrounding atmospheric pressure.

With lower pressure on mountains, water needs less heat to reach its boiling point, so it boils at a lower temperature than the 100°C (212°F) it does at sea level.

Slower Cooking:

Since food cooks based on temperature, boiling it in water that is not as hot (e.g., 92°C at 8,000 feet) means the cooking process takes significantly longer to achieve the same result as at sea level.