I know for number 4 the answer is c, sorry I can't help with the others.
Answer:
d. 127 g/mol.
Explanation:
Hello!
In this case, since we have the amount of molecules of this this compound, we are able to compute the moles out there by using the Avogadro's number:

Which correspond to the moles of X2. Then, by using the mass we are able to compute the molar mass of X2:

It means that the atomic mass of X halves the molar mass of X2, which is then d. 127 g/mol.
Best regards!
The reason we cannot breath liquid water is because the oxygen used to make the water is bound to two hydrogen atoms and we cannot breath the resulting liquid
Answer:
Magnesium Difluoride
Explanation:
Mg = magnesium
F = fluoride
F2 = difluoride (prefix "di" indicates 2)
Answer:
1.7927 mL
Explanation:
The mass of solid taken = 4.75 g
This solid contains 21.6 wt%
, thus,
Mass of
=
= 1.026 g
Molar mass of
= 261.337 g/mol
The formula for the calculation of moles is shown below:
Thus,

Considering the reaction as:

1 moles of
react with 1 mole of 
Thus,
0.003926 mole of
react with 0.003926 mole of 
Moles of
= 0.003926 mole
Also, considering:

Molarity = 2.19 M
So,

Volume = 0.0017927 L
Also, 1 L = 1000 mL
<u>So, volume = 1.7927 mL</u>