Answer:
B. Theory
Explanation:
A theory can be changed as new information is discovered.
Answer:
Water sample showing pink/purple color is an error.
Explanation:
Biuret is a blue color reagent that changes its color to pink/purple whenever it detects protein in a sample. Water don't contain proteins so it should not show pink/purple color instead it should maintain the blue color. Food items generally contain proteins so it show pink/purple color but it showed blue color.
Error might have caused by wrong marking of the samples, test tube marked with Water might contain a mystery food while Mystery food tube might contain water.
Answer:
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Answer:
The correct answer will be- Crop rotation
Explanation:
When the growth of a type of crop which uses soil nutrients in abundance and then growing another crop in the same filed led to the decrease in the production of the next crop.
Thus farmers adapted to avoid such farming practices and developed a new practice which allowed the land to become fertile again so that the growth of next crop will not be affected.
The practice involved the planting of a crop on a piece of land then leaving the soil ploughed and unsown for a longer period of time and growing corp on another piece of land allowing the time to restore the nutrient content. This practice is known as "crop rotation".
Thus, crop rotation is the correct answer.
