Questions

The water cycle is a term for the movement of water between the Earth's surface, the sky and underground. Water evaporates due to heat from the sun. Hence, the water cycle is driven primarily by the energy from the sun.

This solar energy drives the cycle by evaporating water from the oceans, lakes, rivers, and even the soil. Other water moves from plants to the atmosphere through the process of transpiration.

The freezing point of water and melting point is 0 °C or 32 °F. The temperature may be lower if supercooling occurs.

Cholesterol belongs to lipids class of molecules. Lipids are sometimes called as fats which act as storing energy and structural components of cell membranes.

Paper production is basically a two-step process in which a fibrous raw material is first converted into pulp, and then the pulp is converted into paper. The harvestedwood is first processed so that the fibres are separated from the unusable fraction of the wood, the lignin. Pulp making can be done mechanically or chemically. In the chemical pulping process, alkali (e.g., sodium hydroxide in the form of a lye or caustic soda) is usually used to remove the lignin that binds the fibres. So, for degumming of raw material, caustic soda is used.