Chemistry Location

Elements can be classified as metals, non-metals and metalloids on the basis of their physical and chemical properties.  Physical properties of metals: Lustre : Metals in their pure state have a shining surface called metallic lustre. Malleability : Metals are malleable i.e can be beaten into thin sheets. Note : Gold and silver are the most malleable metals. Ductility : The ability of metals to be drawn into thin wires is called ductility.  • Gold is the most ductile metal.  Note : 1 gramof gold can be drawn into a thin wire about 2km long because of their malleability and ductility. Conductivity : Metals are good conductors of heat and electricity • Silver and copper are good (best) conductors of heat and electricity.  • Lead and mercury are comparatively poor conductors of heat and electricity.  Sonorous : Metals are sonorous i.e they produce a sound when hit (strike) with a hard surface (object). • The metals that produce a sound on striking a hard surface a...

Acid :  The chemical substance which are sour in taste , change the colour of blue litmus to red and gives H+ ion in aqueous solution is called acid. There are two types of acids: 1.Strong acids :  An acid which is completely (100%) ionised in water and produces (give rise) large amount (more number) of hydrogen ions (H+ ions) is called a strong acid. Example : Hydrochloric acid (HCl), sulphuric acid (H₂SO₄), nitric acid (HNO₃ ). 2.Weak acids : An acid which is partially (<100%) ionised (do not dissociate completely i.e incomplete ionised) in water and produces (give rise) small amount (number) of hydrogen ions (H+ ions) is called a weak acid. Example : Acetic acid or Ethanoic acid (CH₃COOH), formic acid (HCOOH), Carbonic acid (H₂CO₃), sulphurous acid (H₂SO₃), citric acid, tartaric acid etc. Base : The chemical substance which are bitter in taste , soapy to touch, change the colour of the red litmus to blue and gives OH- ion in aque...

Que : MnO₂ + xHCl → MnCl₂ + yH₂O + zCl₂ In order to balance the above chemical equation, the values of x, y and z respectively are: (a) 6, 2, 2               (b) 4, 1, 2                  (1Marks) (c) 4, 2, 1                 (d) 2, 2, 1                    (2023)  Ans:   Que: Calcium oxide reacts vigorously with water to produce slaked lime. CaO (s) + H₂O → Ca(OH)₂ (aq) This reaction can be classified as: (A) Combination reaction      (B) Exothermic reaction (C) Endothermic reaction                 (1 Marks) (D) Oxidation reaction                         (2020) Which of the following is a correct option? (i) (A) and (C)                ...

• Whenever a chemical change occurs, we can say that a chemical reaction takes place i.e Chemical reactions involve chemical changes. Chemical Change :   • If the identity, composition or nature of a chemical substance change and can not be reserved by any physical process, it is called chemical change . Chemical Reaction :   • The process involving a chemical change is called chemical reaction . • The process in which one or more substance as reactants gets converted (transformed) into new substances with new properties in product as a result of chemical change is called chemical reaction . Reactants :   • The substances that undergo chemical change or takes part in a chemical reaction is called reactants .  Products :   • The new substances produced (formed) during the reaction as a result of chemical change are called products . • Chemical reactions involves the breaking and making of bonds between atoms i.e in a chemical reaction old bonds are b...