Answer:
B. Controlled variables
Explanation:
The Dependent sample t-test compares the mean score of measurements in one group to that of another other group. It mainly used when analyzing comparable sample units as it pairs repeatable observations within a time frame.
Controlled variables are factors that are not tested and remain constant. Some examples of controlled variables are temperature, pressure, volume etc
(C)When acid reacts with base, a salt and a water formed.
The answer would be C) it is always the same as it was before the collision
Answer:c
Explanation: atoms make matter
