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WorksheetsCHEMICAL REACTIONS AND EQUATIONS
Total questions: 17
Worksheet time: 9mins
What happens in a chemical reaction?
Bonds between atoms break and/or are formed
New atoms are created and/or removed
Protons move from one atom to another
Electrons change into protons
Which of the following would indicate that a chemical reaction has occurred?
A new element has been created
A different substance has formed
The total mass has either increased OR decreased
The total number of elements has either increased OR decreased
BEFORE the equation is balanced, how many Hydrogen atoms are present on the reactant side?
6
2
12
8
How many sulfur atoms are present in this molecule?
4
3
12
1
What does the Law of Conservation of Mass state?
No new substances can be made or destroyed
No new compounds can be made or destroyed
No new atoms can be made or destroyed
Mass cannot be lost from a physical reaction
Which of the following follows the Law of Conservation of Mass?
CH₄ + 2 O₂ → 2CO₂ + 2 H₂O
2 CH₄ + 2 O₂ → CO₂ + 4 H₂O
CH₄ + 2 O₂ → CO₂ + 2 H₂O
All the above
In a chemical reaction, ________________________ are changed into _______________________.
Reactants; Products
Electrons; Molecules/Compounds
Coefficients; Subscripts
Original Elements; New Elements
Bacteria in milk causes it to curdle over time. What type of change is this?
Chemical
Physical
Both
Neither
Which type of reaction pulls in thermal energy from the environment around it?
Endothermic
Exothermic
Which of the following is not a physical change?
(a) Boiling of water to give water vapour
(b) Melting of ice to give water
(c) Dissolution of salt in water
(d) Combustion of Liquefied Petroleum Gas (LPG)
Which of the following statements about the given reaction are correct?
3Fe(s) + 4H2O(g) ® Fe3O4(s) + 4H2(g)
(i) Iron metal is getting oxidised
(ii) Water is getting reduced
(iii) Water is acting as reducing agent
(iv) Water is acting as oxidising agent
(a) (i), (ii) and (iii)
(b) (iii) and (iv)
(c) (i), (ii) and (iv)
(d) (ii) and (iv)
Which among the following is(are) double displacement
reaction(s)?
(i) Pb + CuCl2 --> PbCl2 + Cu
(ii) Na2SO4 + BaCl2 --> BaSO4 + 2NaCl
(iii) C + O2 --> CO2
(iv) CH4 + 2O2 --> CO2 + 2H2O
(a) (i) and (iv)
(b) (ii) only
(c) (i) and (ii)
(d) (iii) and (iv)
The following reaction is used for the preparation of oxygen gas in the laboratory
2KClO3 (s) + Heat --Catalyst--> 2KCl (s) + 3O2 (g)
Which of the following statement(s) is(are) correct about the reaction?
(a) It is a decomposition reaction and endothermic in nature
(b) It is a combination reaction
(c) It is a decomposition reaction and accompanied by release of heat
(d) It is a photochemical decomposition reaction and exothermic in nature
Which of the following are combination reactions?
(i) 2KClO3 + Heat --> 2KCl + 3O2
(ii) MgO + H2O --> Mg(OH)2
(iii) 4Al + 3O2 --> 2Al2O3
(iv) Zn + FeSO4 --> ZnSO4 + Fe
(a) (i) and (iii)
(b) (iii) and (iv)
(c) (ii) and (iv)
(d) (ii) and (iii)
Electrolysis of water is a decomposition reaction. The mole ratio of hydrogen and oxygen gases liberated during electrolysis of water is
(a) 1:1
(b) 2:1
(c) 4:1
(d) 1:2
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
(a) (i) only
(b) (ii) only
(c) (iv) only
(d) (ii) and (iv)
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
(a) (i) only
(b) (i) and (iii)
(c) (ii) and (iii)
(d) (iv) only
