Question

How many moles are in 4.24kg of Na2CO3?

Answer 1

Data:
4.24 Kg converting (grams) → 4240 g

Molar Mass of $Na_{2} CO_{3}$
Na = 2*23 = 46 amu
C = 1*12 = 12 amu
O = 3*16 = 48 amu
-------------------------
Molar Mass of $Na_{2} CO_{3}$ = 46 + 12 + 48 = 106 g/mol

If:

106 g → 1 mol
4240 g → y

Solving: Rule of three (directly proportional)
$\frac{106}{4240} = \frac{1}{y}$
multiply cross
106*y = 4240*1
106y = 4240
$y = \frac{4240}{106}$
$\boxed{\boxed{y = 40\:moles}}\end{array}}\qquad\quad\checkmark$

Answer:
B. 40.0 moles