CIE iGCSE Co-Ordinated Science C10.1 Water Exam Style Questions Paper 1
Question
Other than hydrogen and oxygen, which substance provides only one of the essential elements for plant growth?
A. K₃PO₄
B. KNO₃
C. (NH₄)₃PO₄
D. NH₄NO₃
▶️Answer/Explanation
Answer: D
Explanation: NH₄NO₃ (ammonium nitrate) provides only nitrogen, which is one of the essential elements for plant growth. The other substances provide multiple elements.
Question
In order to make water from reservoirs fit to drink, ……1…… is used to kill bacteria. Water in a condenser is used during distillation as a ……2…… . When water is used to make ethanol from ethene, it is acting as a ……3…… . Which words correctly complete gaps 1, 2, and 3?
A. Chlorination, coolant, reactant
B. Chlorination, solvent, solvent
C. Filtration, coolant, reactant
D. Filtration, solvent, solvent
▶️Answer/Explanation
Answer: A
Explanation: Chlorination is used to kill bacteria in water. In distillation, water acts as a coolant in the condenser. When making ethanol from ethene, water acts as a reactant.
Question
What is a chemical test for water?
A. It turns anhydrous cobalt(II) chloride white.
B. It turns anhydrous copper(II) sulfate blue.
C. It turns blue copper(II) sulfate white.
D. It turns pink cobalt(II) chloride blue.
▶️Answer/Explanation
Answer: B. It turns anhydrous copper(II) sulfate blue.
Explanation: Anhydrous copper(II) sulfate (white) turns blue in the presence of water, making it a reliable chemical test for water.
Question
Which colour is observed when water is added to anhydrous copper(II) sulfate?
A) blue
B) green
C) pink
D) white
▶️Answer/Explanation
Answer: A) blue
Explanation: Anhydrous copper(II) sulfate is white, but it turns blue when water is added, forming hydrated copper(II) sulfate.
Question
What is the colour of cobalt(II) chloride after water is added to it?
A blue
B pink
C white
D green
▶️Answer/Explanation
Answer: B pink
Explanation: Cobalt(II) chloride is blue in its anhydrous form, but when water is added, it turns pink due to the formation of a hydrated complex.
Question
Anhydrous cobalt(II) chloride changes colour when water is added.
Which row shows the colour before and after water is added?
▶️Answer/Explanation
Ans :A
Question
Why do farmers add limestone to soil?
A It acts as a fertiliser.
B It adds nitrogen to the soil.
C It decreases the pH of the soil.
D It increases the pH of the soil.
▶️Answer/Explanation
Ans :A
Question
Which colour change is observed when water is tested using copper(II) sulfate?
A blue → pink
B blue → white
C white → blue
D white → pink
▶️Answer/Explanation
Ans :A
Question
Which statement about the treatment of the water supply is correct?
A Chlorination is used to improve the taste of the water.
B Chlorination is used to kill bacteria.
C Filtration is used to adjust the pH of the water.
D Filtration is used to remove soluble impurities.
▶️Answer/Explanation
Ans : B
Question
Which substance turns blue when it is added to pure water?
(A) anhydrous copper(II) sulfate
(B) anhydrous cobalt(II) chloride
(C) red litmus
(D) universal indicator
▶️Answer/Explanation
Ans: A
Question
What is not a use of limestone?
(A) manufacture of calcium oxide
(B) neutralising industrial waste products
(C) purifying water
(D) treating acidic soil
▶️Answer/Explanation
Ans : C
Question
Water is tested with white copper(II) sulfate powder and with blue cobalt(II) chloride paper.
Which row shows the results of the tests?
▶️Answer/Explanation
Ans : B
Question
Four watch-glasses contain solid salts as shown.
Water is added to each salt.
Which statement describes the salt solutions that form?
A They are blue or pink only.
B They are white or blue only.
C They are all pink.
D They are all blue.
▶️Answer/Explanation
Ans : A
Question
Which statement about the treatment of the water supply is correct?
A Water from reservoirs and rivers is filtered to remove dissolved impurities.
B Chlorine is added to the water to kill bacteria.
C Sodium chloride is added to the water to make it pleasant to drink.
D Chlorine is added to make the water pure.
▶️Answer/Explanation
Ans : B
Question
Which statement describes a chemical test for water?
(A) Add blue cobalt(II) chloride.
(B) Add blue copper(II) sulfate.
(C) Measure the boiling point.
(D) Use universal indicator.
▶️Answer/Explanation
Ans : A
Question
Which colours are observed when water is added to white copper(II) sulfate and to blue cobalt(II) chloride?
▶Answer/Explanation
Ans : C
Question
Which compound contains two of the three elements needed in a fertiliser used for plant growth?
(A) potassium carbonate
(B) potassium chloride
(C) potassium nitrate
(D) potassium sulfate
▶️Answer/Explanation
Ans: C
Question
Why is chlorine used in the treatment of water supplies?
A. to bleach water
B. to kill bacteria
C. to remove insoluble compounds
D. to remove soluble compounds
▶️Answer/Explanation
Answer: B. to kill bacteria
Explanation: Chlorine is added to water supplies as a disinfectant to kill harmful bacteria and other microorganisms, making the water safe to drink.
Question
A colourless liquid is added to blue cobalt chloride paper. The paper turns pink. What does this show about the liquid?
A. It contains water.
B. It is acidic.
C. It is neutral.
D. It is pure water.
▶️Answer/Explanation
Answer: A
Explanation: Blue cobalt chloride paper turns pink in the presence of water. This indicates that the liquid contains water (A). It does not necessarily mean the liquid is pure water (D), acidic (B), or neutral (C).
Question
Why do farmers treat their fields with fertilisers?
A. to decrease the acidity of the soil
B. to increase the oxygen content of the soil
C. to increase the water content of the soil
D. to increase the yield of crops
▶️Answer/Explanation
Answer: D. to increase the yield of crops
Explanation: Fertilisers provide essential nutrients like nitrogen, phosphorus, and potassium to the soil, which helps increase the yield of crops by promoting healthy plant growth.
Question
Which statement about fertilisers is correct?
A. They are fed to animals to improve the animals’ growth.
B. They contain only nitrogen, phosphorus and potassium as elements.
C. They increase plant growth by adding chemicals directly to plant flowers.
D. They increase plant growth by adding chemicals to the soil.
▶️Answer/Explanation
Answer: D
Explanation: Fertilizers are added to the soil to provide essential nutrients like nitrogen, phosphorus, and potassium, which promote plant growth. They are not fed to animals, and they do not contain only these three elements. They are applied to the soil, not directly to plant flowers.
Question
When substance X is added to blue cobalt(II) chloride paper, the paper turns pink. What is X?
A ammonia
B an acid
C chlorine gas
D water
▶️Answer/Explanation
Answer: D
Explanation: Cobalt(II) chloride paper turns pink in the presence of water.
Question
Which pie chart represents the composition of clean air?
▶️Answer/Explanation
Answer: C
Explanation: Clean air is composed mainly of nitrogen (78%) and oxygen (21%), with the remaining 1% being other gases. Pie chart C correctly represents this composition.
Question
Which three elements are needed in fertilisers to help plants grow?
A. nitrogen, phosphorus, potassium
B. nitrogen, phosphorus, sodium
C. nitrogen, sodium, potassium
D. sodium, phosphorus, potassium
▶️Answer/Explanation
Answer: A. nitrogen, phosphorus, potassium
Explanation: Nitrogen, phosphorus, and potassium are the primary nutrients required by plants for growth and are commonly found in fertilisers.
Question
Which row describes the colour changes when water is added to anhydrous copper(II) sulfate and to cobalt(II) chloride?
▶️Answer/Explanation
Answer: C
Explanation: Anhydrous copper(II) sulfate is white and turns blue when water is added. Cobalt(II) chloride is blue and turns pink when hydrated.
Question
What is not a use of limestone?
A. manufacture of calcium oxide
B. neutralising industrial waste products
C. purification of water
D. treating acidic soil
▶️Answer/Explanation
Answer: C
Explanation: Limestone is used to manufacture calcium oxide, neutralise acidic waste, and treat acidic soil, but it is not typically used for water purification.