During exercise , his body responds by an increase in the heart rate and his
respiratory rate.
<h3>What is Exercise?</h3>
Exercise refers to the activities which are done to improve the physical
fitness of an individual. Examples include:
The heart and respiratory rate are increased to ensure enough oxygen is
available to the cells of the body. This helps to ensure carbohydrate is
broken down to energy which is used by the body cells during the exercise
being performed.
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Answer:
Fluorine, Chlorine, Bromine, or Iodine
Explanation:
These all have an ALMOST full valence shell. And they need one more electron so they'd react with hydrogen