According to
Graham's Law of Diffusion,"the rates of diffusion of two gases are inversely proportional to the square root of their Molar masses or Densities at the same pressure and temperature".
r₁ / r₂ =

Where,
r₁ = Rate of Helium
r₂ = Rate of Oxygen
M₂ = Molar mass of Oxygen = 32 g/mol
M₁ = Molar mass of Fluorine = 4 g/mol
Putting values,
r₁ / r₂ =

r₁ / r₂ =

r₁ / r₂ =
2.82
Result:
Helium gas effuses
2.82 times faster than Oxygen gas.
False
The water is more buoyant which means the water has more of a tendency to float than the duck.
Answer:
Tree sap flows over the leaf and preserves it.
Explanation:
Amber would preserve the image.
To answer this problem, we need to count the electrons in the given configuration. The complete configuration is 1s2 2s2 2p6 3s2 3p6. There are 2+2+6+2+6 equal to 18 electrons. We find next the element with an atomic number of 18. That element is noble gas argon.
Answer:
The molar concentration of Cu²⁺ in the initial solution is 6.964x10⁻⁴ M.
Explanation:
The first step to solving this problem is calculating the number of moles of Cu(NO₃)₂ added to the solution:

n = 1.375x10⁻⁵ mol
The second step is relating the number of moles to the signal. We know the the n calculated before is equivalent to a signal increase of 19.9 units (45.1-25.2):
1.375x10⁻⁵ mol _________ 19.9 units
x _________ 25.2 units
x = 1.741x10⁻⁵mol
Finally, we can calculate the Cu²⁺ concentration :
C = 1.741x10⁻⁵mol / 0.025 L
C = 6.964x10⁻⁴ M