Modern vacuum pumps can evacuate a vessel down to a pressure of atm

PHYSICS · Single correct · A Level · Physics · Further mechanics and thermal physics · Further mechanics and thermal physics

Problem

Modern vacuum pumps can evacuate a vessel down to a pressure of

4.0 \times 10^{-15}

atm. at room temperature (300 K). Taking

R = 8.0 \text{ JK}^{-1} \text{ mole}^{-1}

1 \text{ atm} = 10^5 \text{ Pa}

and

N_{\text{Avogadro}} = 6 \times 10^{23} \text{ mole}^{-1}

, the mean distance between molecules of gas in an evacuated vessel will be of the order of: (1)

0.2 \mu\text{m}

(2)

0.2 \text{ mm}

(3)

0.2 \text{ cm}

(4)

0.2 \text{ nm}