If you flip a coin 50 times, about how many times would you expect to get heads?

25 times.

Explanation:

The probability of getting 1 out of 2 options will always be 50 if they are equal. Say you had a bag of marbles with 3 blue marbles and 3 red marbles. If you were to pull one out, it would be a 50% chance of getting a red marble. With a penny, you only have one of each thing, but the chance of getting heads would still be 50%, since you still have an equal amount of both things. If you flip it 50 times, you would expect it to be heads about 25 times, since 25 is half of 50, and you have a 50% chance of getting heads.

a) carbon, hydrogen

b) carbon, hydrogen, oxygen, nitrogen

c) carbon, hydrogen, oxygen, nitrogen, phosphorus

d) sugar

e) amino acid

f) nucleotide