Question

Give two reasons to prove that water is a compound and not an element.

Answer 1

Hint: An attempt to this question can be by writing the chemical reaction between hydrogen and oxygen molecules to form water. Show the difference between an element and a compound and how water follows the properties of a compound like no physical method of separation etc. Elements are placed in a periodic table. See if the water is present in the periodic table to identify whether water is an element or not.

Complete step by step solution:
Water is a polar inorganic substance that is tasteless, odourless and almost colourless at room temperature. Water is considered as the universal solvent as many solutes readily dissolve in water. It is the most abundant substance of the earth.
Water exists in a liquid state of matter at 298 K which is considered as room temperature.
Water is formed by the chemical reaction between a hydrogen molecule and an oxygen molecule. Water cannot be separated by physical means like magnetic separation, winnowing, etc. Water can be broken down to its constituent elements through electrolysis which is a chemical reaction.
Along with this the two most important reason that proves water is a compound and not an element is:
-The melting point of water as well as boiling point varied on the external pressure, volume and surrounding temperature. This implies that water is a compound and not an element. This is because an element's properties remain uniform irrespective of external conditions.
-Water is stable at room conditions. This property is mostly observed in compounds and not in elements. Because the elemental state is highly reactive and unstable for elements in general.

Note: Water, unlike other hydrides, exists as a liquid at room temperature. Hydrogen sulphide too cannot exist as a liquid at normal conditions. This is because water molecules exhibit strong hydrogen bonding that keeps the molecules together and thus exist in the liquid state instead of the gaseous state.