How many moles of CO2 are in 1.0L at 25 degrees C and 95 kPa?

The problem with this is which R do you use in PV = nRT. Everything else is straightforward. You can google the multitude of Rs that come about because the only difference is in the units used. Most of the time it is 8.314. When you google, call it the gas constant in PV = nRT. Keep it bookmarked when you are doing problems in this section.

R = 8.314 L kPa / (mol oK)

T = 25oC = 25 + 273 = 298oK

P = 95000 Pa

V = 1.0 L

Now you are all set to find n

Rearrange the formula

n = PV / (RT)

n = 95000 * 1 / (8.314 * 298)

n = 38.343 Seems like an awful lot. But that's what you are getting