Answer:
1.525834 (1.53 when accounting for significant figures).
Step-by-step explanation:
This problem relies on the Ideal Gas Law, PV = nRT, where P is pressure, V is volume, n is moles, R is a specific constant, and T is temperature. In this problem, we are solving for n, moles, so we would rewrite it as n = PV/RT. Since the units here are moles, liters, atmospheres, and kelvin, R would be the value in atmosphere liter per mole kelvin, or 0.0821. From here, you just enter the values in the fraction and calculate.
For the significant figures, I followed the measurement of 34.2 L, giving 3, although an argument could be made for 1 significant figure from 1 atm, I imagine your professor would want something more specific than 2.