General Chemistry Questions for SSC - IBPS - IAS - HCS - UPSC Exams

Complete Review of Chemistry of HCS - IAS - SSC - UPSC Exams 2013 - Just Simple

Chemistry - A Branch of physical science, is the study of the composition, properties & behavior of matter.

Physical Changes :- 

• Changes which only affect the physical properties like colour, hardness, density melting point etc & do not affect the composition & chemical property of matter. It is temporary.

Chemical Changes :-

• It affects the composition as well as chemical properties of matter & results in the formation of new substance. Burning of fuels, candles, papers, electrolysis of water, photosynthesis, ripening of fruits etc are chemical changes.

Boiling Point :- 

• Temperature at which liquid convert in to vapours . Boiling point of water is 100 degree celcius. It increases with the impurities. Due to this fact, boiling point of sea water is more than boiling point of pure water.

Atom, Molecule & Element :- 

• It is the smallest part of a matter that take part in the chemical reactions but can not exists in free state. 
• It is made up of electron, proton & neutron. Proton & neutron reside in the nucleus.
• Electron revolve around nucleus.
• Atoms combine to form molecule & molecule is the smallest part of matter which can exist in free state.
• Element contains only one type of atoms. e.g. carbon (C), sulphur (S), diamond, graphite.

Conceptual Thinking :- 

• At high altitude, the atmospheric pressure is less than sea level & hence water boils at a lower temperature (Less than 100 degree celcius) & food take more time to cook.
• Inside the pressure cooker, pressure is higher & hence, water boils at a higher temperature (i.e. boiling point of water increases) & food is cooked quickly.
• Air escaping from a punctured tyre is cold because the air escaping from a region of high pressure to low pressure.