Prepare for the Punjab Board Class 10 Chemistry Examination 2027 with our Chapter 20: Water – Class Test No. 1. This full unit model paper is designed to help students prepare according to the new Chemistry syllabus issued by PECTAA Punjab. As part of our Punjab Board 2027 Model Papers and Class 10 Chemistry Chapter-Wise Test Series, this test helps students revise important concepts, assess their understanding of the Water chapter, and improve their examination preparation. Practice this Class 10 Chemistry test to strengthen your subject knowledge and prepare confidently for the 10th Class annual board examinations in 2027.
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1. Colour of hydrated copper(II) sulphate is:
(Q-2)
A. WhiteB. GreenC. BlueD. Yellow
Answer: C. Blue – CuSO4·5H2O is blue; on heating it loses water and turns white.
2. Pure water boils at temperature:
(Q-5)
A. 90 °CB. 95 °CC. 100 °CD. 110 °C
Answer: C. 100 °C (at standard pressure, 1 atm).
3. The pH range of tap water is usually:
(Q-12)
A. 1–3B. 4–6C. 6.5–8.5D. 9–12
Answer: C. 6.5–8.5 – safe drinking-water range.
4. Disease is caused by contaminated water is:
(Q-18)
A. DiabetesB. CancerC. CholeraD. Asthma
Answer: C. Cholera – a waterborne disease.
5. Heavy metals mainly damage organs:
(Q-20)
A. Heart and lungsB. Liver and kidneyC. Skin and bonesD. Stomach and intestine
Answer: B. Liver and kidney
6. ______ removes smaller suspended particles by ?
(Q-24)
A. DistillationB. FiltrationC. AerationD. Chlorination
Answer: B. Filtration
7. The annual rainfall in northern Pakistan including Punjab is about:
(Q-37)
A. Below 100 mmB. 250–600 mmC. 800–1000 mmD. Above 1200 mm
Answer: B. 250–600 mm
8. Urea contains nitrogen:
(Q-52)
A. 20%B. 30%C. 46%D. 60%
Answer: C. 46% – urea, CO(NH2)2, is the richest common nitrogen fertilizer.
786Times • Chemistry Chapter-20
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i. Why is water important for life on Earth?
(Q-1)
Ans: Water is the universal solvent for body reactions, carries nutrients and waste, regulates temperature, is needed for photosynthesis, and about 70% of the body is water.
ii. How can the purity of water be tested using boiling point?
(Q-4)
Ans: Pure water boils sharply at 100 °C (1 atm). Impurities raise the boiling point, so if water boils above 100 °C it is impure.
iii. How tap water supplied? Write its sources.
(Q-8)
Ans: Water is pumped from the source to a treatment plant, purified and sent through pipes to homes. Sources: rivers, lakes, canals, springs and underground water (wells, tube wells).
iv. What is distilled water?
(Q-10)
Ans: Very pure water obtained by boiling water and condensing its steam. It is free from dissolved salts and impurities.
v. Write the Name any two waterborne diseases.
(Q-15)
Ans: (1) Cholera (2) Typhoid (also dysentery, hepatitis A).
vi. What are microplastics? Write it’s effect.
(Q-17)
Ans: Microplastics are tiny plastic particles (less than 5 mm). Effects: they pollute water, are swallowed by aquatic animals, enter the food chain and harm human health.
vii. What is sedimentation?
(Q-20)
Ans: The process in which heavy suspended particles settle at the bottom of water when it is left standing.
viii. Mention two ways to control water pollution.
(Q-26)
Ans: (1) Treat industrial and sewage waste before releasing it into water. (2) Avoid throwing garbage and plastic into rivers and lakes.
ix. What are micro-nutrients? Give an example.
(Q-34)
Ans: Nutrients needed by plants in very small amounts. Example: iron (Fe), zinc (Zn), copper (Cu), boron (B).
x. State any four essential requisites of a good fertilizer.
(Q-40)
Ans:
- It must be soluble in water.
- It should contain a high percentage of plant nutrients.
- It must be cheap and easily available.
- It should be stable and not harmful to soil or plants.
SECTION-II (4+4)
1. How domestic water supply can be made fit for drinking?
(Ex.D. 20.1)
Ans: Steps of treatment:
- Screening – removes large floating objects.
- Sedimentation – heavy particles settle.
- Coagulation – alum makes fine particles clump and settle.
- Filtration – sand and gravel beds remove smaller suspended particles.
- Aeration – air removes bad smell and dissolved gases.
- Chlorination – chlorine kills germs, making water safe to drink.
2. What are fertilizers? Mention the essential qualities of a good fertilizer.
Ans: Fertilizers are natural or synthetic substances added to soil to supply essential nutrients (N, P, K) and increase crop yield. Qualities of a good fertilizer:
- Soluble in water so plants can absorb it.
- Rich in nutrients (e.g. urea has 46% nitrogen).
- Not poisonous to plants and soil.
- Cheap, easy to store and transport.
- Stable under normal conditions.
786Times • Chemistry Chapter-20
