1 Marks Important Questions:Chemical Reactions and Equations

  1. Some crystals of copper sulphate were dissolved in water. The colour of the solution
    obtained would be
    (a) green
    (b) red
    (c) blue
    (d) brown.
    Ans. (c) blue
  2. When dilute HCl is added to zinc pieces taken in a test tube
    (a) No change takes place
    (b) the colour of the solution becomes yellow.
    (c) A pungent smelling gas gets liberated.
    (d) small bubbles of H2 gas appear on the surface of zinc pieces
    Ans. (d) small bubbles of H2 gas appear on the surface of zinc pieces.
  3. PbS reacts with ozone (O3) and forms pbso4. As per the balanced equation, molecules
    of ozone required for every one molecule of PbS is / are
    (a) 4
    (b) 3
    (c) 2
    (d) 1
    Ans. (a) 4
  4. Chemically rust is
    (a) Hydrated ferrous oxide

(b) hydrated ferric oxide
(c) only ferric oxide
(d) none of these
Ans. (b) hydrated ferric oxide

  1. Which of the following reactions is not correct
    Ans. (b)
  2. Copper displaces which of the following metals from its salt solution:
    (a) ZnSO4
    (b) FeSO4
    (c) AgNO3
    (d) NiSO4
    Ans. (c) AgNO3
  3. In an electrolytic cell where electrolysis is carried, anode has:
    (a) Positive change
    (b) Negative charge
    (c) Connected to negative terminal of the battery
    (d) None of these is correct.
    Ans. (a) Positive change
  4. The reaction H2+Cl2 2HCl represents :
    (a) Oxidation
    (b) Reduction
    (c) Decomposition
    (d) Combination

In the reaction PbO + C Pb + CO
(a) Pbo is oxidised
(b) C act as an oxidising agent
(c) C act as a reduction agent
(d) Reaction does not represent redox reaction.
Ans. (c) C act as a reduction agent

  1. A substance which oxidizes itself and reduces other is known as
    (a) Oxidising agent
    (b) reducing agent
    (c) Both (a) and (b)
    (d) None of these.
    Ans. (b) reducing agent
  2. Take about 5 ml of dil. HCl in a test tube and add a few pieces of fine granules to it.
    Which gas is evolved?
    (a) Chlorine
    (b) Hydrogen
    (c) HCl
    (d) Nitrogen
    Ans. (b) Hydrogen
  3. Dissolving suger is an example of-
    (a) Physical change
    (b) Chemical change
    (c) Redox Reaction
    (d) None of these.
    Ans. (a) Physical change
  4. Heat is evolved diving

(a) Endothermic Reaction
(b) Displacement Reaction
(c) Combustion Reaction
(d) Combination Reaction
Ans. (c) Combustion Reaction

  1. Which of the following is not a balanced equation?
    Ans. (a)
  2. The reaction between lead nitrate and potassium iodide present in aqueous
    solutions is an example of
    (a) Decomposition Reaction
    (b) Displacement Reaction
    (c) Double Displacement Reaction
    (d) Neutralisation Reaction
    Ans. (c) Double Displacement Reaction
  3. What happens when dilute hydrochloric acid is added to iron filling? 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) is correct.

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