Answer:

Explanation:
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In this case, we can divide the problem in two steps:
1. Dilution to 278 mL: here, the initial concentration and volume are 1.20 M and 52.0 mL respectively, and a final volume of 278 mL, it means that the moles remain the same so we can write:

So we solve for C2:

2. Now, since 111 mL of water is added, we compute the final volume, V3:

So, the final concentration of the 139 mL portion is:

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Isotope ¹⁸F⁻ contains:
1) p⁺ = 9; number of protons.
Fluorine has a<span>tomic number Z = 9 (total number of protons).
2) e</span>⁻<span> = 10; </span>number of electrons.<span>
In element number of electrons and protons are the same, because element has neutral charge, but because in this example, fluorine is anion with negative charge, it has one electron more.
3) n</span>° = 9; number of neutrons.
<span>Mass number
A = 18 is total number of protons and neutrons in a nucleus, so number of neutrons is A-Z = 18-9=9.</span>
Answer:
3'' one is correct answer
Explanation:
in mutualism, organisms of different species benefit from cooperation
Answer:
Mole fraction for C₂₂H₁₉Cl₂NO₃ = 0.0086
Explanation:
Mole fraction remains a sort of concentration. It indicates:
moles of solute / (moles of solute + moles of solvent)
Moles of solute / Total moles.
Solute: Cypermethrin → C₂₂H₁₉Cl₂NO₃
Solvent: Water (PM = 18g/mol)
We calculate moles from solvent: 1000g /18 g/mol = 55.5 moles
We calculate PM for C₂₂H₁₉Cl₂NO₃
12g/mol . 22 + 1g/mol . 19 + 35.45 g/mol . 2+ 14g/mol + 16g/mol . 3 = 416 g/m
Moles of solute: 200 g / 416g/mol = 0.481 moles
Total moles: 0.481 + 55.5 = 55.98 moles
Mole fraction for C₂₂H₁₉Cl₂NO₃ = 0.481 moles / 55.98 moles = 0.0086
Answer:

Explanation:
The fission reaction taking place given in the question is:

The mass is conserved in the reaction.
So,
235 + 1 = A + 94 + 3×1
A = 139 g/mol
Also, number o protons remain same. So,
92 = Z + 36
Z = 56
The isotopic symbol is 