A rigid 10.0 L tank at 25 °C initially contains 4.00 g of He(g) and 40.0 g of Ne(g)

CHEMISTRY · Single correct · A Level · Chemistry · Amount of substance · Amount of substance

Problem

A rigid 10.0 L tank at 25 °C initially contains 4.00 g of He(g) and 40.0 g of Ne(g). Through a small leak, exactly 25 % of the He atoms escape while the amount of Ne remains unchanged. After the leak is sealed and the system returns to 25 °C, what is the average molar mass of the gas mixture inside the tank? (a) 18.0 g mol−118.0\ \text{g mol}^{-1} (b) 15.7 g mol−115.7\ \text{g mol}^{-1} (c) 20.2 g mol−120.2\ \text{g mol}^{-1} (d) 14.8 g mol−114.8\ \text{g mol}^{-1}

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