Warning: mysqli_real_connect(): Headers and client library minor version mismatch. Headers:100508 Library:100236 in /home/u248481792/domains/hpexams.in/public_html/wp-includes/wp-db.php on line 1653
Chemistry (Important facts-1) – HPExams.in
Skip to content
A substance that is used for the removal of excess of chlorine after the bleaching of a substance by chlorine is called antichlor. Aquaregia is mixture of one part nitric acid and three parts of hydrochloric acid. The number of molecules present in one gm mole is called Avogadro’s number. It is equal to 6.023 x 10²³ Sodium Bicarbonate is also called baking soda. Sodium Carbonate (Na2CO310H2O) is commonly called washing soda. Sodium Sulphate (Na2SO410H2O) is commonly called Glauber’s salt. Impure copper having blisters on its surface is called Blister copper. Buffer solution-A solution which prevents the change in pH of some other solution. Carbohydrate -Organic compound with a general formula Cx(H20)x. They form important component of food. Protein – Nitrogenous compounds which are the important constituent of living beings and plants. They are formed from amino acids. A chemical substance that changes the rate of a chemical reaction,without itself undergoing any change is called a catalyst. A substance formed by a fixed ratio of two or more elements is called a compound. Constituents of a mixture can be separated by physical methods. No chemical reaction takes place in a physical change, i.e., no new substance is formed. There are 18 groups and 7 periods in the Long form of Periodic Table. Atomic number was discovered by Moseley. The number of protons and electrons present in an atom is equal. Group number in the Mendeleef’s Periodic Table represents the valency of elements present in that group. The elements of I-A Group are called alkali metals (Li, Na, K,Rb, Cs and Fr). The elements of I-B Group are called coinage metals (Cu, Ag,Au). Mercury is also called quick silver. Calcium oxide (CaO) is commonly called quick lime. Pb,O, is also called Red lead. Chemical composition of rust is Fe2O3xH2O. Sodium carbonate is called soda ash or sal soda. Nitrous oxide (N20) is called laughing gas. Chemical formula of marble is CACO3. NH3, CO, and C,F2CI2 are used as refrigerant. Sodium silicate (Na2SiO3) is called water glass. The alcoholic solution of iodine is called iodine tincture. Formic acid is obtained from red ants. Rold Gold contains 90% copper and 10% aluminium. German silver contains 60% copper, 25% zinc and 15% nickel. The mixture of benzene, petrol and ethyl alcohol is called power alcohol. Fluorine is the most electronegative element. Francium is the most electropositive element. Silver is the best conductor of electricity. Graphite is a non-metal which is the best electrical conductor. Chlorine exhibits highest electron affinity. Platinum is also called white gold. Astatine (At) is the most rare element on earth. Oxygen is the most abundantly found element on earth. Nitrogen is most abundantly found in atmosphere. Petrol is called liquid gold. 24 carat gold is called pure gold. Substances which undergo sublimation on heating-iodine, naphthalene, camphor, ammonium chloride and phthalic acid. The nucleus of only hydrogen atom does not contain neutron. Gold, platinum, mercury and silver are noble metals. Lithium is the lightest metal. Radon is the heaviest gas. Astatine is the heaviest element among solid non-metals. Lithium is the strongest reducing agent. Atom bomb is based upon nuclear fission. Hydrogen bomb is based upon nuclear fusion. Solid carbon dioxide is called dry ice. Only hydrogen is an element whose all the isotopes are named differently (Protium, deuterium and tritium). Thermal decomposition of alkanes is called cracking. Alpha (a) particle is equivalent to helium nucleus. Beta (B) particle is equivalent to electron. Diamond is the hardest element found in nature. Polonium (Po) has largest number of isotopes (27). Sulphuric acid is called oil of vitriol.