A given mass of gas has a pressure of 80 Nm\(^{-2}\) at a temperature of 47 C. If the temperature is reduced to 27 C with volume remaining constant, the new pressure is?

A.

46.0 Nm\(^{-2}\)

B.

75.0 Nm\(^{-2}\)

C.

80.0 Nm\(^{-2}\)

D.

85.3 Nm\(^{-2}\)

Correct answer is B

Using \(\frac{P_{1}}{T_{1}} = \frac{P_{2}}{T_{2}}\)

P\(_{1}\) = 80Nm\(^{2}\)
T\(_{1}\) = 47 + 273 = 320k
T\(_{2}\) = 27 + 273 = 300k
P\(_{2}\)?

\(\therefore\) = P\(_{2}\) = \(\frac{P_{1}T_{2}}{T_{1}}\)

= \(\frac{80 \times 300}{320}\) = 75.Nm\(^{2}\)