Questions

When water is cooled from 4°C to 0°C, its density decreases.

When water cools from 4°C to 0°C, ice crystals begin to form because the water is approaching its freezing point. When water freezes, the water molecules form a lattice that increases the volume. As a result, the density decreases. This is why ice will float on top of water; ice has a lower density than the water.

An enzyme speeds up a reaction by lowering the activation energy which is done by catalysts to increase the rate.

The main source of organic matter in soil is the plant and animal tissue that decompose at each level of breakdown.

Arvari river is a small river in the Indian state of Rajasthan. It just have 90 km of length and it also consider as the smallest river of India and flows through the Arvari District of Rajasthan

Himachal Pradesh government had passed a Bill to make Sanskrit as its 2nd official language.

Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to gain more stability, which is gained by forming a full electron shell. By sharing their outer most (valence) electrons, atoms can fill up their outer electron shell and gain stability.

Examples of compounds with covalent bonds ::

HCl, CO2, O2,...