Se - 78
Selenium - 78
or
78/34 Se2-
Answer:
b. 0.453 mol
Explanation:
To convert atoms to moles, use Avogadro's number (6.022×10²³). Divide the amount of atoms that are given by Avogadro's number. You should get 0.453 mol.

Lithium, Sodium, Potassium; any of the Alkali Metals, which are farthest left on the periodic table. This is because they only have one electron in their outermost shell, so they would rather lose an electron rather than try to gain 7 to achieve that full outer shell.
Answer: Here comes the role of another formula, which we refer to as the structural formula and that is CH3OH for methanol. The structural formula gives us an additional information that carbon is attached to three hydrogen atoms and one oxygen atom.
Answer:
68 g
Explanation:
Molar mass (C10H16) = 10*12.0 g/mol + 16*1.0 g/mol = (120+16)g/mol =
= 136 g/mol
m (C10H16) = n(C10H16)*M(C10H16) = 0.5 mol*136 g/mol = 68 g
n(C10H16) - number of moles of C10H16
M(C10H16) - molar mass of C10H16