Answer:

Explanation:
Here, we want to calculate the number of formula units in the given molecule
We start by getting the number of moles
To get the number of moles, we have to divide the mass given by the molar mass
The molar mass is the mass per mole
The molar mass of calcium bromide is 200 g/mol
Thus, we have the number of moles as follows:

The number of formula units in a mole is:

The number of formula units in 0.2075 mole will be:
Carbonates
OPTION A is the correct answer
Answer : The partial pressure of
and
are, 84 torr and 778 torr respectively.
Explanation : Given,
Mass of
= 15.0 g
Mass of
= 22.6 g
Molar mass of
= 197.4 g/mole
Molar mass of
= 32 g/mole
First we have to calculate the moles of
and
.

and,

Now we have to calculate the mole fraction of
and
.

and,

Now we have to partial pressure of
and
.
According to the Raoult's law,

where,
= partial pressure of gas
= total pressure of gas
= mole fraction of gas


and,


Therefore, the partial pressure of
and
are, 84 torr and 778 torr respectively.
Answer:
2.24dm³
Explanation:
Given parameters:
Mass of He = 40g
Unknown:
Volume of Helium = ?
Solution:
To solve this problem, we convert the given mass to number of moles.
Number of moles =
molar mass of He = 4g/mol
Number of moles =
= 0.1mole
So;
1 mole of gas at rtp occupies a volume of 22.4dm³
0.1 mole of He will occupy a volume of 0.1 x 22.4 = 2.24dm³
Answer:
The formula of ammonium fluoride is NH4F.
Explanation:
1 The atoms in each ion are bonded together covalently to form a single unit.
Wrong!
⇒ The atoms in an ion compound are linked together by an ionic bond.
2 The charge is distributed over the entire ion.
Wrong!
Ions have taken in or given up electrons. This happens in the atomic shell.
3 The formula of ammonium fluoride is NH4F.
Right!
4 The formula of potassium sulfate is K2SO
Wrong!
The formula for potassium sulfate is K2SO4.