Answer:

Explanation:
Hello,
In this case, given the described concept regarding the Avogadro's number, we can easily notice that 27.0 g of aluminium foil has 6.022x10²³ atoms as shown below based on the mass-mole-particles relationship:

Notice this is backed up by the fact that aluminium molar mass if 27.0 g/mol.
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Answer:
MOLARITY= 0.3092mol/l
ABSOLUTE UNCERTAINTY= 0.000873
Explanation:
The equation of reaction is
2HNO3 + Na2CO3 ⟶ 2NaNO3 + H2O + CO2.
QUESTION1: CALCULATION FOR MOLARITY;
Molarity= gram mole of solute ÷ liters of solution
Where;
Mole of solute= mass ÷ molar mass
Therefore;
Mole of solute= 0.8311g ÷ 105.988g/mol= 0.0078515mol
MOLARITY= 0.0078415mol ÷ 25.36ml = 0.0003092mol/ml = 0.3092mol/l
This is the Molarity of the solution
QUESTION2: CALCULATION FOR ABSOLUTE UNCERTAINTY;
Uncertainty (u) =√([0.05 ÷ 25.36]^2 + [0.001 ÷ 105.988]^2 + [0.0007 ÷ 0.8311]^2) × Molarity
Solving brackets gives
(0.00197161+0.00000943503+0.00084226) ×Molarity
Adding up gives
0.002823×Molarity
Therefore;
ABSOLUTE UNCERTAINTY= 0.002823×0.3092= 0.000873
heterogeneous mixture, because, the layers are called phases and a heterogeneous mixture has two or more phases. the oil phase is less dense then water so it floats on top, etc.
Radioactive elements obey 1st order kinetics,
For 1st order reaction, relation between rate constant (k) and half life [t(1/2)] is,
k =

Also, for 1st order reaction, we have
t =
Given that: <span>the bones from a mastodon had lost 78.5% of their C14,
</span>∴ initial conc. of C14 = 100%, conc. of C14 left after time 't' = 21.5%
∴t =

= 1.2758 X 10^4 hours