There are about 1 ✕ 10^5 chemical reactions per second in each of the 10 billion nerve cells in the brain. How many chemical reactions take place in a day in a single nerve cell?

Answer: 8.64 x 10^9

Explanation: To find the solution to this it is best to first calculate the number of seconds in a single day.

A day is made up of 24 hours; an hour is made up of 60 minutes; and each minute comprises of 60 seconds.

Number of seconds in a 24 hour day is given by:

24 hours x 60 minutes x 60 seconds = 86,400 seconds

Now 1 x 10^5 (100000) chemical reactions go on per second in one nerve cell. If there are 86,400 seconds in a day, then total number of chemical reactions is:

86,400 x 100000 = 8,640,000,000

= 8.64 x 10^9 chemical reactions per nerve cell per day.