CBSE ADDA

NCERT Activity Chapter 02 Acid Bases and Salt Class 10 Chemistry Activity 2.1 Indicator Acid Base Red litmus No Change Blue Blue Litmus Red No change Phenolphthalein Colourless Pink Methyl Orange Pink   Yellow Indictors are substance which change colour in acidic or basic media. Activity 2.2 There are some substances whose odour changes in in acidic or basic media. These are called olfactory indicators. Like onion vanilla, onion and clove. These changes smell in basic solution. Activity 2.3 Take about 5 mL of dilute sulphuric acid in a test tube and add few pieces of zinc granules to it. => You will observe bubbles of hydrogen gas on the surface of zinc granules. Zn + H2SO4 --> ZnSO4 + H2 => Pass the Hydrogen gas through the soap solution. Bubbles formed in the soap solution as Hydrogen gas it does not get dissolved in it

X NCERT ACTIVITIES Class 10 Chemical Reactions and Equations Activity 1.1 (Experiment): Activity 1.1 Clean a magnesium ribbon by rubbing it with sandpaper to remove layer of carbonate and oxide. Burn it using a spirit lamp you get white ash of  MgO.            Mg (s) + O 2 (g)      à MgO(s) => Magnesium ribbon burn with dazzling light and white powder of MgO is formed which is basic in nature It is an example of combination reaction in which single compound break into two or more substance. Activity 1.2 (Experiment): Take lead nitrate solution in a test tube. Add potassium iodide solution to this. => Yellow precipitate PbI 2 is formed. Substance Insoluble in water is called precipitate. Pb(NO 3 ) 2   (aq)     +      2KI    à PbI 2 (s) ( ¯ )    +  2 KNO 3   (aq) This is an example of precipitation reaction . This is an example of Double decomposition reaction in which there is exchange of radicals. Activity 1:3 (Experiment): Take a few zinc granules

CBSE ADDA Chapter 1, Chemical Reactions and Equations NCERT Science Textbook In-Text Questions (Answers) (Page 6) Q.1: Why should magnesium ribbon be cleaned before burning in air ? Ans: Magnesium ribbon is a very reactive metal. When stored it reacts with oxygen to form a layer of magnesium oxide on its surface. This layer of magnesium oxide being a stable compound prevents further reaction of magnesium with oxygen. The magnesium is cleaned before burning in air to remove this layer so that the metal can be exposed to air properly. Q.2: Write the balanced equation for the following chemical reactions: (i) Hydrogen + Chlorine --> Hydrogen chloride (ii) Sodium + Water --> Sodium hydroxide + Hydrogen Ans: (i) H2 (g) + Cl2 (g) --> 2HCl (g) (ii) 2Na (s) + 2H2O (liq) --> 2NaOH (aq) + H2 (g). Q.3: Write a balanced chemical equation with state symbols for the following chemical reactions: (i) Solution of barium chloride and sodium sulphate in water t

CBSE ADDA Chapter 1, Chemical Reactions and Equations Solutions of Science Textbook Exercise Questions Q.1: Which of the statements about the reaction below are incorrect? 2PbO + C ---> 2Pb + CO2­ (a) Lead is getting reduced. (b) Carbon dioxide is getting oxidized. (c) Carbon is getting oxidized. (d) Lead oxide is getting reduced. (i) a and b (ii) a and c (iii) a, b and c (iv) all. Ans: (i) a and b. Q.2: Fe2O3 + 2Al ---> Al2O3 + 2Fe The above reaction is an example of a (a) combination reaction (b) double displacement reaction (c) decomposition reaction (d) displacement reaction. Ans: (d) Q.3: What happens when dilute HCl is added to iron filings ? Tick the correct answer. (a) Hydrogen gas and iron chloride are produced. (b) Chlorine gas and iron hydroxide are produced. (c) No reaction takes place. (d) Iron salt and water are produced. Ans: (a) Q.4: What is a balanced chemical equation ? Why should chemical equation be balanced ?

JSUNILTUTORIAL PUNJABI COLONY GALI NO Multiple choice question  CHEMISTRY X   Chemical Reaction and Equations 1. Respiration is: (a) Endothermic reaction (b)Exothermic reaction (c) Addition reaction (d) None 2. Photolysis is: (a) Decomposition (b) Addition (c) Displacement (d) Oxidation 3. Fe2O3 + 3CO → 2Fe + 3CO2, which is reducing agent in the above reacton:  (a) Fe2O3 (b) CO (c) Fe (d) CO2 4. What are the conditions for rusting of an iron article: (a) Presence of air (b) Presence of moisture (c) Both (d) None 5. Plaster of Paris is (a) 2CaSO4.H2O (b) CaSO41/2H2O (c) Both (d) None 6. Oxidation reaction is a chemical process in which a substance: (a) Gains hydrogen (b) Gains oxygen (c) Gains chlorine (d) None  7. Hydration means: a) addition of hydrogen (b) addition of hydrogen chloride (c) addition of sulphuric acid (d) addition of water  8.The decomposition of CaCO3 is (a) an endothermic reactio