Chemical Reactions
1)Which one of the following is not a chemical change?
  

2)A student added a few pieces of zinc into dil.H₂SO₄ taken in a test tube. Suddenly, evolution of gas occurs. What gas is evolved?
  

3)Which product is formed when magnesium burns in air?
  

4)Why do copper sulphate crystals change colour from blue to white on heating?
  

5)Identify X in the following reaction: CuSO₄ (aq)+ H₂S (g)-->X (s) + H₂SO₄ (aq).
  

6)What happens when a small piece of iron is kept in copper sulphate solution?
  

7)Which one of the following is a reversible chemical change?
  

8)While performing an experiment, a student adds sodium sulphate solution to a colourless solution. A white precipitate is immediately formed and is insoluble in dil. HCl. The colourless solution is …………………………… & the precipitate formed is……………………
  

9)When NaOH is added to zinc sulphate solution, a precipitate is formed which is soluble in excess of NaOH. The precipitate obtained is……………………. & the colour of the precipitate is……………….
  

10)Identify the product(s) obtained by the reaction of ZnSO4 (aq) and H2S (g).
  

11)2H₂ + O₂ → 2H₂O is an example of which type of reaction?
  

12)On heating Pb(NO₃)₂, what is observed during the reaction?
  

13)In the reaction Ba(NO₃)₂ + Na₂SO₄ → X + 2NaNO₃, X is:
  

14)Which of the following is an example of combustion?
  

15)Take dilute sulphuric acid in a test tube and put a few zinc granules into the test tube. What will you observe?
  

16)When magnesium combines with oxygen, it produces magnesium oxide that appears to be like:
  

17)When will we observe a precipitate to occur in the solution?
  

18)Barium sulphate is:
  

19)What is observed when burning a magnesium ribbon in air?
  

20)100 ml of a saturated copper sulphate solution was taken in a beaker. A small amount of iron filings was added to the beaker and left undisturbed overnight. The mixture was then filtered to obtain the residue. The residue was found to be what colour?
  

21)When you place an iron nail in copper sulphate solution, the reddish brown coating formed on the nail is _______.
  

22)What is observed when dilute sulphuric acid is added to zinc granules?
  

23)What happens when blue litmus is added to a water extract of MgO?
  

24)Which of the following is a double displacement reaction?
  

25)What is obtained when Cu reacts with silver nitrate?
  

26)Why does iron displace copper from its salt solution?
  

27)Which diagram shows the safest method to detect hydrogen gas produced in a reaction?
  
  

 
 
 
 

28)Which one of the following is not observed, when a magnesium ribbon is burnt in the flame of a Bunsen burner?
  

29)Why is magnesium ribbon held with a pair of tongs and not with bare hands, when it is burnt in air?