CLASS X SA-1 PRACTISE QUESTIONS ANSWERS

ARMY PUBLIC SCHOOL GOLCONDA

PRACTISE QUESTIONS ANSWERS(SA-1) CLASS –X

1.       In combination reactions two substance combines to form one compound and in decomposition reactions a compound breaks down into two or more substances, so they are opposite to each other. 2.      Ionic Bond 3.      Sulphide ore 4.      Carbon dioxide gas. Pass this gas into lime water, it turns into milky white. 5.      KCl(aq)   + AgNO3 (aq)    -------------------------   AgCl(s)        +  KNO3(aq), it’s a double displacement reaction. 6.      X is Calcium Oxide.                                                                                                                                            CaO(s)         +       H2O (l)   -----------------------    Ca(OH)2(aq)   7.      (a)  C +  O2  -------------------------   CO2                                                                                                           (b) C6H12O6 +  6O2  6CO2 +  6H2O +  energy                                                                                            (c)  Sulphur dioxide and Sulphur Trioxide. 8.      (i)  It will not undergo any colour change because the solution of Na2SO4(sodium sulphate) in water is almost neutral.                                                                                                                                                 (ii)  Concentrated sulphuric acid is highly hygroscopic. It absorbs moisture from air and gets diluted. Since the volume increases, the acid starts flowing out of the bottle. 9.      Washing soda - Na2CO3 . 10 H2O Baking soda : NaHCO3               Baking soda is an ingredient of anatacids. It neutratlises HCl released in stomach and ceases  stomach ache.                                   NaHCO3 + HCl ----------------------------            NaCl + CO2 +H2O 10.  Definition : Homogeneous mixture of two or more metals or a metal and a non metal. Preparation : (i) Melting the primary metal. (ii) Dissolving the other elements in a definite proportion and cooled to room temperature.                                                   Alloy Constituent Uses                       Brass Cu and Zn in making utensils 1                       Bronze Cu and Tin making statue,  medal                           Solder Pb and Tin in soldering . 11.  (i)  In nature metals are found in free and combined forms, i.e. as their compounds.                                                                                                                                                    (ii)  With oxygen : All metals combine with oxygen and form metal oxides.                                                                                                                                                                    For examples : When copper is heated in air it combines with oxygen and forms copper oxide.  Metals react with water : For example, sodium reacts with cold water, Mg reacts with hot water, Fe reacts with steam or any other examples.                                                                                                    With Acids : Metals react with acids and form salt and hydrogen gas.                                                   For example : Magnesium reacts with dilute hydrochloric acid and forms magnesium chloride and water.  Equation :  2Cu+O2 -------------------------   2CuO Mg + 2HCl----------- MgCl2 + H2                                                                                                                                                                        2Na(s)+  2H2O(l)------------------------------------ 2NaOH(aq)        +     H2 (g) 12.  (b) 13.  (b) 14.  ( c ) 15.  (d) 16.  (c) 17.  CaCO3          -------------------------------  CaO        +       CO2, Calcium carbonate decomposes to calcium oxide and carbon dioxide on heating. 18.   They get tarnished by reacting with atmospheric air to form silver sulphide. 19.  Oxides which react with both acids and bases are called amphoteric oxides. Example ZnO and  Al2O3. 20.                 2 FeSO4 -----------------------------------  Fe2O3  +  SO2  +  SO3, it is thermal decomposition reaction. 21.       Pb(NO3)2 - lead nitrate                                                    2 Pb(NO3)2  ----------------------------       2 PbO + 4 NO2 + O2 22.   (a) Quick lime reacts vigorously with water to produce slaked lime releasing a large amount of heat.                                                                                                                                                                                 (b) CaO   +  H2O  --------------------------------   Ca(OH)2                                                                                                                                                                                                            (c) Combination reaction . 23.   Sodium Carbonate Decahydrate                                                                                                    Na2CO3.10H2O                                                                                                                                                                           Obtained by heating baking Soda and Recrystallization                                                                                                                                                2NaHCO3    ----------------------------- Na2 CO3 +   H2O    + CO2                                                                                                                                                                               Na2CO3 + 10H2O  -------------------------------Na2CO3.10 H2O 24.    (a) Chlor-alkali-process - explanation                                                                                                       (b) (i) 7 (ii) less than 7 25.    (i) Iron forms its oxide by reacting with oxygen in air. Design of activity - Conditions needed for iron nails to rust. (Air, water) Explanation.                                                                                                                                                                                    (ii) Rusting of iron can be prevented by painting the surface of iron object. Oxygen and moisture of the atmosphere will not be able to come in direct contact with the surface of iron. 26.  (a) 27.  (b) 28.  ( c) 29.  (a)