Answer:
7 protons
Isotopes are atoms that have the same number of protons but different numbers of neutrons in the nucleus. You know that nitrogen-14 has 7 protons in the nucleus because it is an isotope of nitrogen, which has an atomic number equal to 7 .
Oxygen is more <u>electronegative</u> than Hydrogen
So . . .
When the two form covalent bonds, oxygen pulls the electrons closer and farther from hydrogen
So . . .
The water molecule is <u>polar</u>, with oxygen more negative and hydrogen more positive.
So . . .
Since opposites attract, the more negative oxygens attract the more positive hydrogens of other water molecules, forming the <u>hydrogen bonds.</u>
Answer:
Solution's mass = 200.055 g
[PbSO₄] = 275 ppm
Explanation:
Solute mass = 0.055 g of lead(II) sulfate
Solvent mass = 200 g of water
Solution mass = Solvent mass + Solution mass
0.055 g + 200 g = 200.055 g
ppm = μg of solute / g of solution
We convert the mass of solute from g to μg
0.055 g . 1×10⁶ μg/ 1g = 5.5×10⁴μg
5.5×10⁴μg / 200.055 g = 275 ppm
ppm can also be determined as mg of solute / kg of solution
It is important that the relation is 1×10⁻⁶
Let's verify: 0.055 g = 55 mg
200.055 g = 0.200055 kg
55 mg / 0.200055 kg = 275 ppm
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.
