Chemical Reaction & Equations (Objectives)

 

 

Q.1. Magnesium ribbon is rubbed before burning because it has a coating of
(a) basic magnesium carbonate
(b) basic magnesium oxide
(c) basic magnesium sulphide
(d) basic magnesium chloride

Answer

Answer: a

Q.2.  The chemical formula of lead sulphate is     
(a)  Pb₂SO₄
(b)  Pb(SO₄)₂
(c)  PbSO₄
(d)  Pb₂(SO₄)₃

Answer

Answer: c

Q.3. When green coloured ferrous sulphate crystals are heated, the colour of the crystal changes because
(a) it is decomposed to ferric oxide
(b) it loses water of crystallisation
(c) it forms SO₂
(d) it forms SO₃

Answer

Answer: b

Q.4.  Which information is not conveyed by a balanced chemical equation?     
(a)  Physical states of reactants and products     
(b)  Symbols and formulae of all the substances involved in a particular reaction     
(c)  Number of atoms/molecules of the reactants and products formed     
(d)  Whether a particular reaction is actually feasible or not

Answer

Answer: d

Q.5. In which of the following chemical equations, the abbreviations represent the correct states of the reactants and products involved at reaction temperature?
(a) 2H₂ (l) + O₂ (l) > 2H₂O(g)
(b) 2H₂ (g) + O₂ (l) > 2H₂O (l)
(c) 2H₂ (g) + O₂ (g) > 2H₂O (l)
(d) 2H₂ (g) +O₂ (g) > 2H₂O (g)

Answer

Answer: d

Q.6.  Chemically rust is     
(a)  hydrated ferrous oxide
(b)  only ferric oxide
(c)  hydrated ferric oxide
(d)  none of these

Answer

Answer: c

Q.7. A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disap¬pears. Which of the following is the correct explanation for the observation?
(a) KMnO₄ is an oxidising agent, it oxidises FeSO₄.
(b) FeSO₄ acts as an oxidising agent and oxidises KMNO₄.
(c) The colour disappears due to dilution; no reaction is involved.
(d) KMnO₄ is an unstable compound and de-composes in presence of FeSO₄. to a colourless compound.

Answer

Answer: a

Q.8.  Both CO₂ and H₂ gases are     
(a)  heavier than air
(b)  colourless
(c)  acidic in nature
(d)  soluble in water

Answer

Answer: b

Q.9. Pb + CuCl₂ → PbCl₂ + Cu
The above reaction is an example of:
(a) combination
(b) double displacement
(c) decomposition
(d) displacement

Answer

Answer: d

Q.10.  Which of the following gases can be used for storage of fresh sampel of an oil for a long time?     
(a)  Carbon dioxide or oxygen
(b)  Nitrogen or helium     
(c)  Helium or oxygen
(d)  Nitrogen or oxygen

Answer

Answer: b