BUDS PUBLIC SCHOOL, DUBAI
REVISION WORKSHEET
Class: 10 Subject: Chemistry
1. Write the balanced chemical equation for the following reaction and identify the type of reaction and define it.‘ Iron III oxide reacts with Aluminum and gives molten iron and aluminum oxide’. (2)
2. Name the following : (a) A metal which is preserved in kerosene
(b) A lustrous coloured non metal (c) A metal which can melt while kept on palm. (d) A metal, which is a poor conductor of heat. (2)
3. Identify the type of chemical reaction and also write the chemical equation for the reaction that takes place when a solution of potassium chloride is mixed with silver nitrate solution. Write the chemical name of one of the products obtained. (2)
4. Why do ionic compounds have high melting points? State reason. (2)
5. Write balanced chemical equations for the following reactions (i) Silver bromide on exposure to sun light decomposes into silver and bromine (ii) Sodium metal reacts with water to form sodium hydroxide and hydrogen gas. (2)
6. Write two observations that you will make when an iron nail is kept in an aqueous solution of Copper Sulphate? Write the chemical equation for this reaction. (2)
7. A reddish brown coloured metal, used in electrical wires, when powdered and heated strongly in an open china dish, its colour turns black. When hydrogen gas is passed over this black substance, it regains its original colour. Answer the following questions. (i) Name the metal and the black coloured substance formed.
(ii) Write balanced chemical equations for both the reactions. (3)
8. (a) Give an example for a combination reaction which is exothermic.
(b) Identify the oxidising agent, reducing agent in the following reaction.
H2 S-+Cl2 à 2HCl+S
(c) Name the phenomenon due to which the taste and smell of oily food changes
when kept for a long time in open. Suggest one method to prevent it. (3)
9. (a) Write the name given to bases that are highly soluble in water .Give an example. (b) How is tooth decay related to pH ? How can it be prevented ?
(c) Why does bee sting cause pain and irritation ? Rubbing of baking soda on the
sting area gives relief. How ? (3)
10. (a) Why is calcium starts floating when added to water ?
(b) Most of the metals do not give hydrogen while reacting with nitric acid. Why ?
(c) Write equation for the reaction of iron with steam. Name the compound of iron
obtained. (3)
11. Silver Chloride is exposed to sunlight. Answer the following questions.
(a) Identify the type of chemical reaction that will take place and define it. How will the colour of the salt change? (b) Write the chemical equation of the reaction that takes place. (c) Mention one commercial use of this salt. (3)
12. What is rancidity? Mention any two ways by which rancidity can be prevented. (3)
13. Differentiate between strong and weak acids. Identify the strong and weak acids
from the following list of acids.
Hydrochloric acid, Acetic acid, Formic acid, Nitric acid. (3)
14. (a) Explain the formation of ionic compound CaO with electron dot structure.
Atomic number of calcium and oxygen are 20 and 8 respectively.
(b) Name the constituent metals of bronze. (3)
15. A small amount of quick lime is added to water in a beaker.
(a) Name and define the type of reaction that has taken place. (b) Write balanced
chemical equation for the above reaction. Write the chemical name of product.
(c) State two observations that you will make in the reaction. (3)
16. Write balanced chemical equation for the reactions that take place during
Respiration. Identify the type of combination reaction that takes place during this
process and justify the name. Give one more example of this type of reaction. (3)
17. A compound which is prepared from gypsum, has the property of hardening when
mixed with right quantity of water. (i) Identify the compound and write its chemical . formula. (ii) Write the chemical equation for its preparation
(iii) List any two uses of the above compound. (3)
18. Give reasons for the following
(i) Ionic compounds have high melting point and boiling point.
(ii) Ionic compounds conduct electricity in molten state.
(iii) Ionic compounds are solids at room temperature and are somewhat hard. (3)
19. (a) In the formation of compound between two atoms A and B, A loses two electrons
and B gains one electron. (i) What is the nature of bond between A and B?
(ii) Suggest the formula of the compound formed between A and B.
(b) On similar lines explain the formation of Mg Cl2 molecule.
(c) Common salt conducts electricity only in the molten state. Why?
(d) Why is melting point of NaCl high? (5)
20. (a) Carbon cannot be used as reducing agent to obtain Mg from MgO. Why?
(b) How is sodium obtained from molten sodium chloride ? Give equation of the
reactions. (c) How is copper obtained from its sulphide ore? Give equations. (5)
21. (a) Identify the acid and the base whose combination forms the common salt that
you use in your food. Write its formula and chemical name of this salt.Name
the source from where it is obtained.
(b) What is rock salt ? Mention its colour and the reason due to which it has this
colour. (c) What happens when electricity is passed through brine ? Write the
chemical equation for it. (5)
22. (a) Write the chemical name and chemical formula of washing soda.
(b) How is it obtained from sodium chloride? Give equations of the reactions.
(c) Why it is called a basic salt? Give its anyone use. (5)
23. (a) Write the chemical name of the coating that forms on silver and copper articles
when these are left exposed to moist air. (b) Explain what is galvanisation .
What purpose is served by it ? (c) Define an alloy. How are alloys prepared?
How do the properties of iron change when
(i) small quantity of carbon, (ii) nickel and chromium are mixed with it. (5)
24. (a) Differentiate between roasting and calcination. Explain the two with the help of
suitable chemical equations. How is zinc extracted from its ore.
(b) Name two metals that can be used to reduce metal oxides to metals. (5)
25. Describe an activity with diagram to illustrate that the reaction of metal
carbonates and metal bicarbonates with acids produces carbon dioxide.
Write the relevant equations of all the reactions that take place. Name any two
forms in which calcium carbonate is found in nature. (5)
26. (a) Write the common name of CaOCl2. How is it prepared? Write the chemical
equation of the reaction involved in the process. Give any two uses of it.
(b) Write the chemical name of washing soda. How is it prepared? Give the
relevant chemical equations. (5)
27. (i) Explain the steps for extraction of copper from its sulphide ore. Write the
balanced equations involved in the process.
(ii) What is meant by refining of metals?Draw a diagram of electrolytic refining of
copper and name the substances used as cathode, anode and the electrolyte.(5)
28. How is the method of extraction of metals high up in the reactivity series different
from that for metals in the middle ? Why the same process cannot be applied for
them ? Explain giving equations, the extraction of sodium. (5)
29. (i) Name the gas which is liberated when an acid reacts with a metal ? How will
you test the presence of this gas ?
(ii) Write the chemical equation for the reaction of zinc metal with
(a) Hydrochloric acid and (b) with sodium hydroxide. Write the chemical name of salt obtained in each case.
(iii) Identify the acid and base for ammonium chloride salt. What would be the
nature of this salt ? Mention the pH range of this salt. (5)
30. (i) Explain why is hydrochloric acid a strong acid and acetic acid, a weak acid ?
How can it be verified ?
(ii) Explain why aqueous solution of an acid conducts electricity.
(iii) You have four solutions A, B, C and D. The pH of solution A is 6, B is 9, C is 12
and D is 7, (a) Identify the most acidic and most basic solutions.
(b) Arrange the above four solutions in the increasing order of H+ ion.
(c) State the change in colour of pH paper on dipping in solution C and D. (5)
Multiple questions(1mark)
31. When ferrous sulphate crystals are heated, the colour of the residue formed is
(a) red (b) brown (c) orange (d) green
32. A small amount of quick lime is taken in a beaker. Water is added slowly to the
beaker. Which of the following observations were noted?
(a) Hissing sound and the solution becomes hot
(b) No characteristic sound and solution turns cold
(c) Hissing sound and the solution becomes cold.
(d) No characteristic sound and the solution becomes hot.
33. The colour of pH strip turned red when it was dipped in a sample. The sample could
be (a) dilute NaOH solution (b) tap water
(c) dilute HCl solution (d) dilute NaHCO3 solution
34. The correct method of finding pH of solution is to :
(a) Heat the solution in the test tube and expose the pH paper to the vapours formed.
(b) Pour solution from the test tube on pH paper
(c) Drop the pH paper into the solution (d) Add a drop of solution on the pH paper
using a dropper.
35. 10 mL of HCl and 10 mL of NaOH solutions are taken in two separate beakers
labelled I and II respectively. On adding Zinc granules to both,it is observed that at
room temperature (a) Gas is evolved vigorously in both (b) Gas is evolved vigorously
in beaker I and not in the beaker II (c) Gas is evolved vigorously in beaker II but
not in the beaker I (d) No gas is evolved in either of the two beakers.
36. A new iron nail is placed in a beaker containing aqueous copper sulphate solution.
When the nail is taken out after 15 minutes, its surface is coated with
(a) reddish deposit (b) greenish deposit (c) black deposit (d) white deposit
37. A piece of granulated Zn was dropped into copper sulphate solution. After some time
the colour of solution changed from (a) light green to blue (b) blue to colourless
(c) light green to colourless (d) blue to green
38. A piece of granulated Zn was dropped into copper sulphate solution. After some time
the colour of solution changed from (a) light green to blue (b) blue to colourless
(c) light green to colourless (d) blue to green
39. The colour of the precipitate formed when barium chloride solution reacts with
sodium sulphate solution is : (a) yellow (b) orange (c) green (d) white
40. A student adds a few drops of universal indicator to a solution and observes colour
changes to orange. The solution would be : (a) strong acid (b) strong base
(c) weak acid (d) weak base
41. When hydrochloric acid reacts with zinc : (a) Surface of zinc becomes white.
(b) surface of zinc becomes black and dull. (c) zinc becomes powder.
(d) the reaction mixture turns red.
42. Freshly prepared iron sulphate solution was taken in each of four test tubes. Strips
of Cu, Fe, Zn and Al were introduced in different test tubes, a black residue was
observed in two test tubes. The pair of metals forming the residue is : (a) Cu and Zn
(b) Al and Cu (c) Fe and Al (d) Zn and Al
43. A student added a piece of zinc metal to four test tubes I, II, III, IV which
respectively contain aqueous solution of aluminium sulphate, zinc sulphate,
ferrous sulphate and copper sulphate. In which solution he observed that the
reaction has taken place. (a) I, II (b) II, III (c) III, IV (d) I, IV