Unit Test: Chemical Reactions & Equations | Science Class 10 PDF Download

Time: 1 hour

M.M. 30

Attempt all questions.

• Question numbers 1 to 5 carry 1 mark each.
• Question numbers 6 to 8 carry 2 marks each.
• Question numbers  9 to 11 carry 3 marks each.
• Question number 12 & 13 carry 5 marks each

Q1: Which of the following reactions is an endothermic reaction?    (1 Mark)
(a) Burning of coal.
(b)  Decomposition of vegetable matter into compost.
(c)  Process of respiration.
(d)  Decomposition of calcium carbonate to form quicklime and carbon dioxide.  

Q2: The following reaction is an example of a 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)    (1 Mark)
(i) Displacement reaction
(ii) Combination reaction
(iii) Redox reaction
(iv) Neutralisation reaction
(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (iii)
(d) (iii) and (iv) 

Q3: Why is hydrogen peroxide kept in colored bottles?    (1 Mark)

Q4: N₂ + 3H₂ → 2NH₃, name the type of reaction.    (1 Mark)

Q5: Why do silver articles become black after some time when exposed to air?    (1 Mark)

Q.6. In the equations given below, state giving reasons, whether substances have been oxidised or reduced. (2 Mark)
(i) PbO + CO → Pb + CO₂
(ii) H₂S + Cl₂ → 2HCl + S

Q7: Can rancidity retard by storing foods away from the light?  (2 Mark) 

Q8: What are the different ways can make more informative about the chemical equation?  (2 Mark) 

Q9: The action of heat on ferrous sulphate is an example of a decomposition reaction.  (3 Mark) 

Q10: 2 g of ferrous sulphate crystals are heated in a dry boiling tube. Answer the following :
(i) List any two observations.
(ii) Name the type of chemical reaction taking place.
(iii) Write the chemical equation of the reaction.  (3 Marks)

Q11: Write the balanced chemical equations for the following reactions  (3 Marks)
(a) Sodium carbonate on reaction with hydrochloric acid in equal molar concentrations gives sodium chloride and sodium hydrogencarbonate.
(b) Sodium hydrogencarbonate on reaction with hydrochloric acid gives sodium chloride, water and liberates carbon dioxide.
(c) Copper sulphate on treatment with potassium iodide precipitates cuprous iodide (Cu₂ I₂ ), liberates iodine gas and also forms potassium sulphate.

Q12: Identify the type of chemical reaction in the following statements and define each of them :
(i) Digestion of food in our body
(ii) Rusting of iron
(iii) Heating of manganese dioxide with aluminum powder.
(iv) Blue color of copper sulphate solution disappears when iron filings are added to it.
(v) Dilute hydrochloric acid is added to sodium hydroxide to form sodium chloride and water.  (5 Marks)

Q13: What happens when zinc granules are treated with dilute solution of H₂SO₄, HCl, HNO₃, NaCl and NaOH, also write the chemical equations if reaction occurs.  (5 Marks)