(g solute/g solution)*100 = % mass/mass
30 g / 400 * 100
0,075 * 100
= 7,5% w/w
hope this helps!
It is actually Group 3A elements. I just took the test.
Answer:
66.2 % of O
Explanation:
Our compound is the lithium nitrite.
LiNO₂
This salt is ionic and can be dissociated: LiNO₂ → Li⁺ + NO₂⁻
We determine the molar mass:
molar mass of Li + 3 . molar mass of N + 6 . molar mass of O
6.94 g/mol + 3. 14 g/mol + 6 . 16 g/mol = 144.94 g/mol
The mass of oxygen contained in 1 mol of lithium nitrite is:
6 . 16 g/mol = 96 g
So the percentage of oxygen present is:
(96 g / 144.94 g) . 100 = 66.2 %
Selenium falls in the same column with oxygen therefore it has the same number of valence electrons with oxygen which is 6. It fills the 3d orbital but only 4s and 4p are counted. The electronic configuration is [Ar]3d^10 4s^2.
