The answer is (3) Cu2O. Copper (I) has an oxidation state of +1 (that's what the "I" indicates). You can also think of this as copper (I) having a charge of +1. Oxygen has an oxidation state of -2 (that's just a rule you have to know), and you can think of it as oxygen having a charge of -2. You need oxidation numbers in a neutral compound to add up to 0 (or charges in a neutral compond to add up to 0), so you need two Cu to balance the O, which is Cu2O.
The answer would be a planet<span>. Planets revolve around stars, which means there will come a point where the planet is between the star and our field of vision towards the star. This point will be where the star's radiation will have the lowest intensity. As the planet moves, the intensity will change. The effect is comparable to a lunar or solar eclipse.</span>
.513mol x (102g/1mol)
Essentially, this is .513 x 102
Which equals: 52.326
But because you can only have 3 significant figures, your answer is:
52.3 grams
I hope this Helps!
We may apply a mass balance here. The total moles of NaCl will remain constant before and after the mixing of the solutions. We have three solutions:
1) 25 ml of 5 M NaCl
2) 100 ml of 0 M NaCl
3) A mixture of these solutions with volume 125 ml and concentration C
The moles of a substance are equal to the product of the concentration and volume. Thus:
25 * 5 + 100 * 0 = 125 * C
C = 1 M
The concentration of the final solution is 1 M.
