Achemist is studying the effects of minerals on plant growth. she knows that phosphorus stimulates plant growth. she decides to test the effects of various phosphorus concentrations on plants every 5 days over a 20 day period. what is the independent variable in this experiment a. amount of plant growth b. phosphorus concentration c. time of experiment d. types of plants

Option B

Explanation:

A chemist is performing an experiment in which he is testing the effect of various phosphorus concentration on the growth of plants.

She decides to change the concentration of phosphorus on every 5th day over a total growth period of 20 days.

The growth of plants will change according to change in concentration of phosphorus. So, the concentration of phosphorus is independent variable.

Hence, the correct answer is option B  

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds