Answer: Yes the statement is true.
Explanation: Endorphins are chemicals produced by the human bodies to relieve stress and pain.
They are produced mainly by brain and help to transmit electrical signals within nervous system, thus are called as neurotransmitters.
They are also called as "feel good chemicals" as they can act as pain relievers and happiness booster and thus lead to better emotional health.
Answer:
No, 22.09% is not a valid measurement
Explanation:
Precision has to do with how close a given set of measured values are to each other. It is quite different from accuracy. Accuracy refers to how close a given set of values is to the true value. A given set of values may be precise but not accurate and vice versa.
If we look at the values obtained; 22.09%, 22.15%, 22.18%, 22.23%, 22.25%, the value 22.09% is too far off the other values. This implies that it does not represent a valid measurement since it is not close to all the other values obtained.
Answer:

Explanation:
The formula for efficiency is

Data:
Useful energy = 3 J
Energy input = 30 J
Calculation:

Emitted/given off. exo is a way to remember that is is going away. think of a flame. the heat is emitted off onto you.
Answer:
Subatomic particles making up an atom
Explanation:
Atom is the smallest unit of any matter
An atom consists of three subatomic particles - Protons, Neutrons, Electrons. Major atomic mass is in the nucleus ie a tiny deep area at the centre. Nucleus consists nucleons, which includes protons (positively charge) & neurons (neutrally charged). Negatively charged electrons are outside the central nucleus.