# area below curve in the left tail
lower <- pnorm(0, mean = 0, sd = 1)

# area below curve from -infinity
# to right tail
upper <- pnorm(0, mean = 0, sd = 1)

# proportion in tails (2 * because symmetry)
2 * lower
[1] 1
# proportion in bulk
upper - lower
[1] 0

# critical values for the proportions
qnorm(lower, mean = 0, sd = 1)
[1] 0
qnorm(upper, mean = 0, sd = 1)
[1] 0