Important Questions Test: Water - UPSC MCQ

Water (H₂O) is a compound composed of hydrogen and oxygen in a fixed ratio.

• Element Check: Elements are single atoms, so water isn't an element.
• Solution Analysis: Solutions require a solute and solvent; pure water has neither.
• Mixture vs Compound: Mixtures can be separated physically, unlike compounds which need chemical reactions.
• Conclusion: Water is a compound due to its fixed composition of hydrogen and oxygen.

The process of changing water vapour into water is called condensation. This process occurs when water vapour in the air cools down and changes back into liquid form.

Rain is a form of precipitation, which refers to water falling to Earth in various forms such as:

• Rain
• Snow
• Hail

Water is not blue in colour.

Water is colorless because all light (except tiny bit of blue) is reflected back. 

Transpiration is the process by which moisture is carried through plants from roots to small pores on the underside of leaves, where it changes to vapor and is released to the atmosphere. Transpiration is essentially evaporation of water from plant leaves. Transpiration also cools plants, changes osmotic pressure of cells and enables mass flow of mineral nutrients and water from roots to shoots.
Therefore, the correct answer is option A.

The purest form of water is rain water as no impurities is present in it.But when it comes to earth, the gases present in the atmosphere gets mixed with it and hence makes it impure but rainwater is pure when it fells from clouds.

Well is underground source of water while river, lake and sea are surface source of water.

The gaseous state of water is called vapour, which is formed by the processes of:

• evaporation
• boiling

The thick envelop of air around the earth is called atmosphere, which contain nitrogen and oxygen gas mainly.

Water naturally exists in all three states on Earth: as ice (solid), liquid water, and water vapour (gas). This is a result of the water cycle, where water continuously transitions between these states due to environmental conditions such as temperature and pressure.

The other substances listed do not naturally occur in all three states within typical environmental settings.