Questions

The difference between Greenwich Mean Time & Indian Standard Time is 5 1/2 hours.

The compound methane is a simple hydrocarbon contains one carbon bonded to four hydrogens. Ethane is a simple hydrocarbon which contains two carbon atoms and four hydrogen atoms. Similarly, propane with three carbons.

Spanish Armada

In a concentrated solution there is a large amount of solute.

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,...

In all the above given options, there is no chemical change or reactions takes place only the shape or physical state is changed.