To investigate the water pollution level of the water samples from three stations of a river

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Manipulated : Types of water sample

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Responding : Time taken for methylene blue to turn colourless.

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Constant : Volume of water samples, volume of methylene blue solution

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Apparatus (A)

Reagent bottles, bottle stoppers, a syringe, a stopwatch, beakers.

Materials (M)

0.1% methylene blue solution, water samples from the 3 stations, distilled water.

Objective	To investigate the water pollution level of water samples from 3 stations of the river.
Problem statement	What is the level of pollution for the water samples from the 3 stations of the river?
Hypothesis	Water near the housing area is the most polluted followed by mouth of river and source of the river.
Variables
Apparatus and materials
Technique	Record the time taken for the methylene blue solution to turn colourless using a stopwatch.
Procedure	1. Collect water samples from different sources of the river. 2. Label the reagent bottles, Station 1 : source of the river, Station 2 : near a housing area, Station 3 : mouth of the river 3. Collect samples of river water from 3 different stations. 4. Fill the reagent bottles with 100 ml of water samples collected. 5. Place all the bottles in a dark cupboard. 6. Use a syringe to add 1ml of 0.1 % the methylene blue solution to the based of each water sample. 7. Record the time taken for the methylene blue solution to turn colourless.
	Precaution 1. Close the reagent bottle with a stopper immediately after adding the methylene blue solution. 2. The contents of the bottles cannot be shaken.
Recording data/ result	Station Water sample Time taken for methylene blue solution to decolourise (minit) 1 Source of the river 2 Near a housing area 3 Mouth of the river
Conclusion	Water near the housing area is the most polluted followed by mouth of river and source of river. Hypothesis is accepted.