2). A student collects 425 L of oxygen at a temperature of 24.0°C and a pressure of 0.899 atm. How many moles of oxygen did the student collect?

15.5 moles

Explanation:

Applying,

PV = nRT Equation 1

Where P = pressure, V = Volume, n = number of mole, R = molar gas constant, T = Temperature.

Make n the subject of the equation

n = PV/RT Equation 2

From the question,

Given: P = 0.899 atm, V = 425 L, T = 24 °C = (273+24) K = 297 K.

Constant: R = 0.083 L.atm/K.mol

Substitute these values into equation 2

n = (0.899×425)/(297×0.083)

n = 15.5 moles

it's c. elements are placed in rows based on how may valencies electrons have.