Answer: BF3
Explanation: boron needs 4 electron to obtain octet and Fluorine has just one. For the valence shell to be completely filled it will have to form BF4- with 4 fluorine atom surrounding it.
My answer to this question is C
B. Developing theories using many lines of evidence
Answer: 8.30 g of calcium sulfate are produced from 10 grams of lithium sulfate.
Explanation:
To calculate the moles :
According to stoichiometry :
1 mole of
require = 1 mole of
Thus 0.061 moles of
will require=
of
Thus
is the limiting reagent as it limits the formation of product and
is the excess reagent.
As 1 mole of
give = 1 mole of
Thus 0.061 moles of
give =
of
Mass of
Thus 8.30 g of calcium sulfate are produced from 10 grams of lithium sulfate.