Vale verga no se what grade tho ?
Answer:
The answer to your question is 1.36 x 10²³ atoms
Explanation:
Data
number of atoms = ?
mass of the sample = 34.2 g
Molecule = Cl₂O₅
Process
1.- Calculate the molar mass of Cl₂O₅
Cl₂O₅ = (35.5 x 2) + (16 x 5) = 71 + 80 = 151 g
2.- Calculate the atoms of Cl₂O₅
151 g of Cl₂O₅ ---------------- 6 .023 x 10²³ atoms
34.2 g of Cl₂O₅ ------------ x
x = (34.2 x 6.023 x 10²³) / 151
x = 1.36 x 10²³ atoms
Answer:
0.14 lb
Explanation:
The <em>half-life</em> of U-235 (703.8 ×10⁶ yr) is the time it takes for half the U to decay.
After one half-life, half (50 %) of the original amount will remain.
After a second half-life, half of that amount (25 %) will remain, and so on.
We can construct a table as follows:
No. of Fraction Amount
<u>half-lives</u> <u>t/(yr × 10⁶)</u> <u>remaining</u> <u>remaining/lb
</u>
1 703.8 ½ 1.1
2 1408 ¼ 0.55
3 2111 ⅛ 0.28
4 2815 ¹/₁₆ 0.14
We see that 2815 × 10⁶ yr is four half-lives, and the amount of U-235 remaining is 0.14 lb.
