To know the exact amount of sodium hydroxide that the teacher needs to order, we need to know how many students are there and the amount that each student uses.
We will then multiply these two values and get the amount needed to be ordered.
Since you have not provided such data in your question, I will just assume them to show the steps of the solution. You can then apply these steps to the values you have.
Now, assume that a class of 60 students and that each student needs to use 130 grams of sodium hydroxide to use during the lab.
This means that the teacher will order:
130 x 60 = 7800 grams = 7.8 kg of sodium hydroxide
Answer: The molar mass of the unknown compound is 200 g/mol
Explanation:
Depression in freezing point is given by:

= Depression in freezing point
i= vant hoff factor = 1 (for molecular compound)
= freezing point constant = 
m= molality

Weight of solvent (benzene)= 0.250 kg
Molar mass of solute = M g/mol
Mass of solute = 26.7 g


Thus the molar mass of the unknown compound is 200 g/mol
Answer:
I THINK it's D, I could be incorrect, however.
Explanation:
C3H8O, as it is flammable, and thus I wouldn't imagine it being a product of combustion. I could be incorrect, so take my answer with a grain of salt.
Answer is: the name of the unknown oxyanion is hypobromite.
<span>
M(NaBrO</span>ₓ) = 118.9 g/mol; <span>molecular weight of an ionic compound.
</span>M(Na) = 23 g/mol; atomic weight of sodium.
M(Br) = 79.9 g/mol; atomic weight of bromine.
M(O) = 16 g/mol; atomic weight of oxygen.
M(Na) + M(Br) + M(O) = 23 g/mol + 79.9 g/mol + 16 g/mol.
M(Na) + M(Br) + M(O) = 118.9 g/mol, so compound is NaBrO and oxyanion is BrO⁻.