Dimensions of the room in cm = 2.54 x 12 by 15 x 2.54 by 2.54 x 8.5 = 30.48 by 38.1 by 21.59
Volume of the room in cubic cm = 30.48 x 38.1 x 21.59 cubic cm = 25,072.21 cubic cm
Given that the density of air at room temperature is

, thus the mass of air in the room = 25,072.21 x 0.00118 = 29.59 g = 0.0296 kg
Given that the lethal dose of HCN is approximately 300 mg HCN per kilogram of air when inhaled, thus the <span>amount of HCN that gives the lethal dose in the small laboratory room is given by 300 x 0.0296 =
8.88 mg.</span>
Answer:
explanations: we multiply with a rational surd
(x-9)*√(x+9)/(√(x-9)*√(x+9)
=(x-9)√(x+9)/

B.( x-9)/√x+3 =( x-9)*(√x-3)/(√x+3)*(√x-3)
= (x-9)*(√x-3)/x-9
=√x-3
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