The controlled experiments are performed by the scientists, when they want to study the changes in the sample on changing a single variable. So, the correct answer is option (b).
In case, all variables are kept same, no changes would be observed in the experiment sample. A controlled experiment can be performed on living thing as well as non living. But, controlled experiment cannot be performed on the things which are influenced by a lot of variables, as they cannot create realistic results. So, the option (a), (c), and (d) are incorrect.
The correct answer is tympanometer. A tympanometer is not used to measure hearing, but to rather measure the transmission of energy through the middle ear. In this way, tympanometry is an objective test of the function of the middle-ear. Tympanometry is used alongside other measures to asses hearing, such as pure tone audiometry.
Answer: 133 km/h
Explanation
Answer:
A scientific law is a statement based on repeated experimental observations that describes some aspect of the universe
Explanation:
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It helps move wastes out of the cell and allows water and nutrients to move into the cell
