Sixty liters of a gas were collected over water when the barometer read 663 mmhg , and the temperature was 20∘c. what volume would the dry gas occupy at standard conditions? (hint: consider dalton's law of partial pressures.)

First, let's compute the number of moles in the system assuming ideal gas behavior. 

PV = nRT
(663 mmHg)(1atm/760 mmHg)(60 L) = n(0.0821 L-atm/mol-K)(20+273 K)
Solving for n,
n = 2.176 moles

At standard conditions, the standard molar volume is 22.4 L/mol. Thus,

Standard volume = 22.4 L/mol * 2.176 mol = 48.74 L

7is b8 is d9 is c10 is a11 is d

No. an alpha particle is a pair of protons and a pair of neutrons, i.e. a helium