Question

1. scientists is investigating whether erosion along the padma river is linked to human - caused changes in the river’s chemical properties. which collection method would result in data related to these properties?

measure differences in the speed of water flow around bridges that span the river.
collect and test water samples at multiple points affected by agricultural runoff.
measure and compare water levels upstream and downstream of dams along the river.
compare the amount of water absorbed by samples of sand and soil near riverside construction sites.

Explanation:

To get data related to the river's chemical properties, we need a method that directly examines the water's chemical composition. Measuring water flow speed (first option) is a physical property. Measuring water levels (third option) is also a physical aspect. Comparing water absorption by sand and soil (fourth option) is about soil/sand properties, not the river's chemical properties. Collecting and testing water samples (second option) can analyze chemical substances like nutrients, pollutants etc. in the water which are related to chemical properties.

Answer:

Collect and test water samples at multiple points affected by agricultural runoff.