AIEEE Questions

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A chemical reaction in which involves the absorption of heat from the environment is called a Endothermic reaction. 

Examples : Dissolving ammonium chloride in water, photosynthesis, melting ice cubes, mixing of potassium chloride with water,...

In the contrast, chemical reactions involving release of heat are known as exothermic reactions.

Examples : Combustion, coal is burnt, mix of CaO with water,...

The distance around a figure is called as Perimeter of that figure. For example, rectangle perimeter is 2(L+B) and where as perimeter of square is '4S'.

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,... 

Photosynthesis is the process that converts solar energy into chemical energy. During the stage of light-dependent reactions involving photosystems I and II in photosynthesis, O2 produced.

Tetrad is a homologous chromosome pair in the given options. A homologous chromosome pair is a pair of chromosomes one from father and one from mother that has same gene sequence after the process of meiosis.