EDUCATRIX

 Mirrors are polished or smooth surfaces, normally a glass coated with a metal amalgam. It can reflect clear image. Plane mirrors  A plane mirror is a mirror with a flat reflective surface.  Spherical mirrors  Spherical mirrors are mirrors which have reflective surface either curved inwards or outwards. It can be considered as a part of a sphere. A spherical mirror, whose reflecting surface is curved inwards (facing towards Center of sphere) is called as concave mirror. A spherical mirror in which reflecting surface is curved outwards is called as convex mirror  In the diagram above shaded part is back side of the mirror 

 REACTION OF ZINC GRANULES WITH DILUTE SULPHURIC ACID After set the apparatus as shown in diagram, add dilute sulphuric acid to test tube and put a few pieces of zinc granules in to it. We can observe, gas bubbles are formed inside the test tube. This gas will carried to soap solution by delivery tube. Soap bubbles filled with the gas raises up from soap solution. If we keep a lighted candle near to that bubble, then gas will burn with pop sound, because that is hydrogen (hydrogen is highly inflammable gas). Thus we can understand hydrogen gas is produced, when acid react with metal.

 Reaction of Acid with metal When metals react with acid, generally metal will displaces hydrogen atoms from the acid as hydrogen gas and forms a compound called salt. That’s  Acid + metal —> salt + hydrogen gas Examples for reaction of acid with metal  1. Zinc + sulphuric acid—>  zinc sulphate + hydrogen  Zn + H₂SO₄ —> ZnSO₄ + H₂ 2.Magnesium + hydrochloric acid—> magnesium chloride + hydrogen gas Mg + 2HCl—> MgCl₂ +H₂ Reaction of base with Metal  Similarly, Base react with metal and produce hydrogen gas and salt. Base + Metal—> Salt + Hydrogen Gas Example for reaction of base with metal  1. Reaction of sodium hydroxide  with zinc to produce sodium zincate and hydrogen gas NaOH + Zn —> Na₂ZNnO₂ + H₂ 2. Sodium hydroxide in presence of water, react with aluminium and produce sodium aluminate and hydrogen gas  2NaOH + 2H₂O + 2Al —> 2NaAlO₂ + 3H₂