1 is oxygen
2 is c=1 O=2
3 is 10
4 is 4 C 12 H
5 is 4 Na 2S 8 O
Answer:
1/16
Explanation:
From the question given above, the following data were obtained:
Half-life (t½) = 269 years
Time (t) = 1076 years
Fraction remaining =?
Next, we shall determine the number of half-lives that has elapsed. This can be obtained as follow:
Half-life (t½) = 269 years
Time (t) = 1076 years
Number of half-lives (n) =?
n = t / t½
n = 1076 / 269
n = 4
Thus, 4 half-lives has elapsed.
Finally, we shall determine the fraction of the original amount remaining. This can be obtained as follow:
Let N₀ be the original amount.
Let N be the amount remaining.
Number of half-lives (n) = 4
Fraction remaining (N/N₀ ) =?
N = 1/2ⁿ × N₀
N = 1/2⁴ × N₀
N = 1/16 × N₀
Divide both side by N₀
N/N₀ = 1/16
Thus, the fraction of the original amount remaining is 1/16
2Na(s) + 2 H2O (liquid) -> 2 NaOH (aq) + H2 (g)
1) 2 reactants are given, so we have to find which of them is an excess reactant and which of them will react completely.
Convert gram of Na and H2O into moles.
M(Na) =23.0 g/mol
10.0 g Na*1 mol Na/23.0 g Na≈0.4349 mol Na
M(H2O) = 2*1.0 +16.0 = 18.0 g/mol
50.0 g H2O*1 mol H2O/18.0 g H2O =2.778 mol H2O
2Na(s) + 2 H2O (liquid) -> 2 NaOH (aq) + H2 (g)
from equation 2 mol 2 mol
given 0.4349 mol 2.778 mol
We can see that H2O is an excess reactant, so we are going to find amount of H2 using Na.
2)
2Na(s) + 2 H2O (liquid) -> 2 NaOH (aq) + H2 (g)
from equation 2 mol 1 mol
given 0.4349 mol x mol
x=(0.4349*1)/2 =0.21745 mol H2
3) mass of H2
0.21745 mol H2 * 2.0 g H2/1 mol ≈ 0.435 g H2
Answer : 0.435 g H2.
I agree with you I doubt that helium is highly flammable.
Answer:
The attraction between two atoms that already participate in other chemical bonds is a hydrogen bond