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ONLY CHEMISTRY TEST 01 Time: 2 Hours
Class: 10 (Science) Max. Marks: 80
General Instructions: All questions are compulsory.
Chemical equations should be balanced.

Section A (Multiple Choice Questions) - 1 Mark Each [20 Marks]

  1. Magnesium ribbon is rubbed before burning because it has a coating of:
    • Basic magnesium carbonate
    • Basic magnesium oxide
    • Basic magnesium sulphide
    • Basic magnesium chloride
  2. Which of the following reactions is an endothermic reaction?
    • Burning of coal
    • Decomposition of vegetable matter into compost
    • Process of respiration
    • Decomposition of calcium carbonate to form quick lime and carbon dioxide
  3. Which of the following gives the correct increasing order of acidic strength?
    • Water < Acetic acid < Hydrochloric acid
    • Water < Hydrochloric acid < Acetic acid
    • Acetic acid < Water < Hydrochloric acid
    • Hydrochloric acid < Water < Acetic acid
  4. The ability of metals to be drawn into thin wires is known as:
    • Ductility
    • Malleability
    • Sonority
    • Conductivity
  5. Cinnabar is an ore of:
    • Copper
    • Zinc
    • Mercury
    • Lead
  6. The functional group present in propanal is:
    • -OH
    • -COOH
    • -CO-
    • -CHO
  7. In which of the following compounds, -OH is the functional group?
    • Butanone
    • Butanol
    • Butanoic acid
    • Butanal
  8. Which of the following statements is true for acids?
    • Bitter and change red litmus to blue
    • Sour and change red litmus to blue
    • Sour and change blue litmus to red
    • Bitter and change blue litmus to red
  9. Which of the following metals reacts with cold water vigorously?
    • Iron
    • Aluminium
    • Calcium
    • Potassium
  10. Amphoteric oxides are:
    • Metal oxides which react with both acids and bases
    • Metal oxides which react with acids only
    • Metal oxides which react with bases only
    • Non-metal oxides which react with acids
  11. The process of coating iron with zinc to prevent rusting is called:
    • Alloying
    • Painting
    • Galvanization
    • Greasing
  12. Ethanol reacts with sodium and forms two products. These are:
    • Sodium ethanoate and hydrogen
    • Sodium ethanoate and oxygen
    • Sodium ethoxide and hydrogen
    • Sodium ethoxide and oxygen
  13. When iron nails are added to copper sulphate solution, the colour changes from blue to light green. This is due to the formation of:
    • Copper iron sulphate
    • Iron sulphate
    • Copper sulphate (colourless)
    • Iron oxide
  14. The chemical formula of Plaster of Paris is:
    • CaSO4.2H2O
    • CaSO4.H2O
    • CaSO4.1/2H2O
    • 2CaSO4.H2O
  15. The electronic configuration of an element 'X' is 2, 8, 6. To which group and period of the modern periodic table does 'X' belong?
    • Group 16, Period 3
    • Group 6, Period 3
    • Group 16, Period 2
    • Group 6, Period 2
  16. Carbon forms four covalent bonds by sharing its four valence electrons with four univalent atoms, e.g. hydrogen. After the formation of four bonds, carbon attains the electronic configuration of:
    • Helium
    • Neon
    • Argon
    • Krypton
  17. Which gas is evolved when dilute HCl reacts with sodium carbonate?
    • Hydrogen
    • Oxygen
    • Carbon dioxide
    • Chlorine
  18. Removal of oxygen from a substance is called:
    • Oxidation
    • Corrosion
    • Reduction
    • Rancidity
  19. Which of the following is not an ionic compound?
    • KCl
    • HCl
    • CCl4
    • NaCl
  20. Vinegar is a solution of:
    • 50% - 60% acetic acid in alcohol
    • 5% - 8% acetic acid in alcohol
    • 5% - 8% acetic acid in water
    • 50% - 60% acetic acid in water

Section B (Very Short Answer Questions) - 2 Marks Each [12 Marks]

  1. Why does the colour of copper sulphate solution change when an iron nail is dipped in it? Write the balanced chemical equation.
  2. What is the role of acid in our stomach? What happens if it is produced in excess?
  3. Ionic compounds have high melting points. Why?
  4. Draw the electron dot structure of (i) Methane (CH4) and (ii) Carbon dioxide (CO2).
  5. Differentiate between roasting and calcination with one example each.
  6. Oil and fat containing food items are flushed with nitrogen. Why? Explain the term used for the spoilage of such food items.

Section C (Short Answer Questions) - 3 Marks Each [21 Marks]

  1. A metal 'X' is treated with dilute sulphuric acid and a gas 'Y' is evolved. The gas 'Y' burns with a pop sound.
    (a) Name the gas 'Y'.
    (b) Describe the test for gas 'Y'.
    (c) Write a balanced chemical equation for the reaction of Zinc with dilute Sulphuric acid.
  2. What is a homologous series? State any two characteristics of homologous series.
  3. Explain the cleansing action of soap. Why are soaps not effective in hard water?
  4. Write the balanced chemical equations for the following reactions:
    (i) Calcium carbonate reacts with dilute hydrochloric acid.
    (ii) Manganese dioxide is heated with aluminium powder.
    (iii) Steam is passed over red hot iron.
  5. Explain the formation of Magnesium Chloride (MgCl2) by the transfer of electrons. State the nature of the bond formed.
  6. Why is respiration considered an exothermic reaction? Explain with the help of a chemical equation.
  7. What are structural isomers? Draw the structures of two isomers of Butane (C4H10).

Section D (Long Answer Questions) - 5 Marks Each [15 Marks]

  1. (a) Define 'Water of Crystallization'. Give two examples of salts containing water of crystallization.
    (b) What happens when Plaster of Paris is mixed with water? Write the chemical equation.
    (c) How is Bleaching Powder prepared? Give its chemical formula and two uses.
  2. (a) Differentiate between ethanol and ethanoic acid on the basis of:
        (i) Physical state
        (ii) Reaction with sodium carbonate.
    (b) Write the chemical equation for the reaction between ethanol and ethanoic acid in the presence of conc. H2SO4. Name the product formed.
    (c) What is the role of conc. H2SO4 in the above reaction?
  3. (a) Explain the following terms with one example each:
        (i) Corrosion
        (ii) Rancidity
    (b) A student took solutions of Aluminium sulphate, Copper sulphate, and Iron sulphate in three different test tubes. He then added iron filings to each of them. In which test tube(s) will he observe a color change? Write the reaction involved.
    (c) Why are food cans coated with tin and not with zinc?

Section E (Case Study Based Questions) - 4 Marks Each [12 Marks]

  1. Case Study 1: pH in Everyday Life
    Our body works within the pH range of 7.0 to 7.8. Living organisms can survive only in a narrow range of pH change. When pH of rain water is less than 5.6, it is called acid rain. When acid rain flows into the rivers, it lowers the pH of the river water. The survival of aquatic life in such rivers becomes difficult. Plants require a specific pH range for their healthy growth.
    1. What is the nature of toothpastes used to prevent tooth decay? [1]
    2. How does antacid help in relieving indigestion? [1]
    3. A farmer treats the soil of his field with quick lime (CaO) or slaked lime. What is the nature of the soil? Explain why. [2]
  2. Case Study 2: Chlor-Alkali Process
    Sodium hydroxide is produced by the electrolysis of a concentrated aqueous solution of sodium chloride (called brine). Chlorine gas is given off at the anode, and hydrogen gas at the cathode. Sodium hydroxide solution is formed near the cathode. This process is very important in industry.
    1. Why is this process called the chlor-alkali process? [1]
    2. Name the products formed at the anode and cathode respectively. [1]
    3. Write the balanced chemical equation for the chlor-alkali process. Mention one use of Hydrogen gas produced. [2]
  3. Case Study 3: Reactivity Series
    The reactivity series is a list of metals arranged in the order of their decreasing activities. After performing displacement experiments, the following series (known as the reactivity or activity series) has been developed. Metals above hydrogen are more reactive than hydrogen and those below hydrogen are less reactive than hydrogen.
    1. Which metal is the most reactive in the activity series? [1]
    2. Can Copper displace Iron from Iron Sulphate solution? Why? [1]
    3. What happens when Zinc granules are added to Copper Sulphate solution? Write the observation and equation. [2]