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Published on: 27/07/2018
Based on the current academic syllabus, some of the important questions are prepared from the chapter Chemical Reactions and Equations.
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Questions + Answers key
Take MCQ Science Test
1.
(a) Write chemical equations.
(i) When carbon dioxide gas is passed through lime water.
(ii)When excess of carbon dioxide gas is passed through lime water.
(b) List two natural forms of calcium carbonate.
2.
(a) In the following reactions, name the reactants, which undergoes oxidation and reduction:
(i) CuO(s) + H2(g) \(\longrightarrow \) Cu(s) + H2O(g)
(ii)CuO(s) + Zn(s) \(\longrightarrow \) ZnO(s) + Cu(s)
(b) State one industrial application of reduction.
3.
Write the balanced equation for the following chemical reactions.
(i) Hydrogen + Chlorine \(\rightarrow\) Hydrogen chloride
(ii) Barium chloride + Aluminium sulphate \(\rightarrow\) Barium sulphate + Aluminium chloride
(iii) Sodium + Water \(\rightarrow\) Sodium hydroxide + Hydrogen
4.
Name the different forms of energy required for breaking down the reactants in decomposition reaction.
5.
Give the formula for quicklime.
6.
Name the gases evolved when lead nitrate is heated.
7.
Name the chemical used in black and white photography.
8.
Write the decomposition of ferrous sulphate with balanced chemical equation.
9.
Write the balanced chemical equations for the following reactions.
(a) Calcium hydroxide + Carbon dioxide \(\rightarrow\) Calcium carbonate + Water
(b) Zinc + silver nitrate \(\rightarrow\) Zinc nitrate + Silver
(c) Aluminium + Copper chloride \(\rightarrow\) Aluminium chloride + Copper
(d) Barium chloride + Potassium Sulphate \(\rightarrow\) Barium sulphate + Potassium chloride
10.
Give an example of a double displacement reaction other than the reaction of barium chloride with sodium sulphate.
11.
Why does the colour of copper sulphate solution change when an iron nail is dipped in it?
12.
A solution of a substance 'X' is used for white washing.
(i) Name the substance 'X' and write its formula.
(ii) Write the reaction of the substance 'X' named in (i) above with water.
13.
Methane on combustion gives
neither CO2 nor H2O
CO2
both CO2 and H2O
H2O
14.
Chemically rust is
only ferric oxide
hydrated ferrous oxide
hydrated ferric oxide
none of these
15.
Which one of the following processes involves chemical reactions?
Storing of oxygen gas under pressure in a gas cylinder.
Liquefaction of air.
Keeping petrol in a china dish in the open.
Heating copper wire in presence of air at high temperature.
16.
Which of the following gases can be used for storage of fresh sample of an oil for a long time?
Carbon dioxide or oxygen
Carbon dioxide or helium
Nitrogen or oxygen
Helium or nitrogen
17.
Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is
1 : 1
2 : 1
4 : 1
1 : 2
18.
Barium chloride on reacting with ammonium sulphate forms barium sulphate and ammonium chloride. Which of the following correctly represents the type of the reaction involved?
(i) Displacement reaction
(ii) Precipitation reaction
(iii) Combination reaction
(iv) Double displacement reaction
(i) only
(ii) only
(iv) only
(ii) and (iv)
19.
Which among the following statement(s) is (are) true? Exposure of silver chloride to sunlight for a long duration turns grey due to
(i) the formation of silver by decomposition of silver chloride
(ii) sublimation of silver chloride
(iii) decomposition of chlorine gas from silver chloride
(iv) oxidation of silver chloride
(i) only
(i) and (iii)
(ii) and (iii)
(iv) only
20.
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 disappears. Which of the following is the correct explanation for the observation?
KMnO4 is an oxidising agent, it oxidises FeSO4
FeSO4 acts as an oxidising agent and oxidises KMnO4
The colour disappears due to dilution; no reaction is involved
KMnO4 is an unstable compound and decomposes in presence of FeSO4 to a colourless compound.
21.
Which of the following is not a physical change?
Boiling of water to give water vapour.
Melting of ice to give water.
Dissolution of salt in water.
Combustion of Liquefied Petroleum Gas(LPG).
22.
What happens when dilute hydrochloric acid is added to iron fillings? Tick the correct answer
Hydrogen gas and Iron chloride are produced.
Chloride gas and Iron hydroxide are produced.
No reaction takes place
Iron salt and water are produced
23.
On adding a drop of barium chloride solution to an aqueous solution of sodium sulphite, white precipitate is obtained.
(a) Write a balanced chemical equation of the reaction involved.
(b) What other name can be given to this precipitation reaction?
(c) On adding dilute hydrochloric acid to the reaction mixture, white precipitate disappears. Why?
24.
What happens when a piece of
(a) Zinc metal is added to copper sulphate solution?
(b) Aluminium metal is added to dilute hydrochloric acid?
(c) Silver metal is added to copper sulphate solution? Write the balanced chemical equation if the reaction occurs.
1.
(a) (i) Ca(OH)2 + CO2\(\longrightarrow \) CaCO3 + H2O
(ii) Ca(OH)2(aq) + CO2(g)\(\longrightarrow \) CaC03(s) +H2O(I)
CaCO3(s) + H2O(I) + CO2(g) \(\longrightarrow \) Ca(HCO3)2 (aq)
(b) Aragonite and calcite
2.
(a) (i) The reactants are copper oxide and hydrogen. Copper oxide undergoes reaction and hydrogen (H2) undergoe oxidation.
(ii) The reactants are copper oxide and zinc. Zinc undergoes oxidation and copper oxide undergoes reduction.
(b) Calcium carbonate is reduced in industries to get CaO and CO2.
3.
(i) H2 + Cl2 \(\rightarrow\) 2HCI
(ii) 3BaCl2 + Al2(SO4)3 \(\rightarrow\) 3BaSO4 \(\downarrow\)+ 2AlCl3
(iii) 2Na + 2H2O \(\rightarrow\) 2NaOH + H2
4.
Heat, light and electricity.
5.
Calcium oxide (CaO), commonly known as quicklime
6.
Nitrogen dioxide gas (reddish brown in colour) and Oxygen gas (colourless).
7.
Silver bromide.
8.
2FeSO4(s) → Fe2O3(s) + SO2(g) + SO3(g)
9.
(a) Ca(OH)2 + CO2 \(\rightarrow\) CaCO3 + H2O
(b) Zn + 2AgNO3 \(\rightarrow\) Zn(NO3)2 + 2Ag
(c) 2Al + 3CuCl2 \(\rightarrow\) 2AlCl3 + 3Cu
(d) BaCl2 + K2SO4 \(\rightarrow\) BaSO4 + 2KCl
10.
The following reaction is an example of a double displacement reaction:
2NaOH (aq) + H2SO4 (aq) \(\rightarrow\) Na2SO4(aq) + 2H2O (l)
Sodium hydroxide Sulphuric acid Sodium sulphate Water
11.
The colour of copper sulphate solution changes when an iron nail is dipped in it because iron being more reactive than copper, displaces copper metal from aqueous copper sulphate solution. Thus, blue colour of copper sulphate fades away to give green colour solution of ferrous sulphate.
Fe (s) + CuSO4(aq) \(\rightarrow\) FeSO4(aq) + Cu(s)
Grey Blue Green Brown
12.
(i) Substance X is calcium oxide or quicklime. Its formula is CaO
(ii) Quicklime reacts with water as:
CaO(s) + H2O(l) \(\rightarrow\)Ca(OH)2 (aq)
X Water Slaked lime (Calcium hydroxide)
13.
(c)
both CO2 and H2O
14.
(c)
hydrated ferric oxide
15.
(c)
Keeping petrol in a china dish in the open.
16.
(d)
Helium or nitrogen
17.
(b)
2 : 1
18.
(d)
(ii) and (iv)
19.
(b)
(i) and (iii)
20.
(a)
KMnO4 is an oxidising agent, it oxidises FeSO4
21.
(d)
Combustion of Liquefied Petroleum Gas(LPG).
22.
(a)
Hydrogen gas and Iron chloride are produced.
23.
(a) A white precipitate of barium sulphite is formed when barium chloride is added to the solution of sodium sulphite.
\(\underset{Barium\\ Chloide}{BaCl_2} +\underset{Sodium\\ sulphite}{ Na2S03} \rightarrow \underset{Baru\ sulphate\\ (white\ ppt)}{ BaS03\downarrow} +\underset{Sodium\\ chloride}{2NaCI}\)
(b) This precipitation reaction is also a double displacement reaction.
(c) Barium chloride, suphur dioxide and water are formed when dilute hydrochloric acid is added to this solution of barium sulphite. Since barium chloride is a soluble substance, thus white precipitate of barium sulphite disappears.
\(\underset { Barium\ sulphate\\ (white\ ppt) }{ BaCl_{ 2 } } +\underset { Hydrochloric\\ acid }{ 2HCl(aq) } \rightarrow \underset { Barium\\ chloride }{ BaC{ l }_{ 2 }(aq) } +\underset { Sulphur\\ dioxde }{ { SO }_{ 2 } } +\underset { Water }{ { H }_{ 2 }O } \)
24.
(a) Zinc sulphate and copper is formed when zinc reacts with copper sulphate,
\(\underset{Zinc}{Zn( s)} + \underset{Copper\ sulphate}{CuSO_4} (aq) \rightarrow \underset{Zinc\ sulphate}{ZnSO_4(aq)} + \underset{Copper}{Cu}\)
(b) Hydrochloric acid forms aluminium chloride and hydrogen gas when reacts with aluminium metal.
\(2AI + 6HCI\rightarrow 2AlCl_3 + 3H_2\)
(c) When silver metal is added to copper sulphate solution, no reaction takes place because silver is less reactive than copper
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