To answer these questions we use the formula

$\text{molecular weight} \times \text{number of moles} = \text{mass of substance (in grams)}$.

a)

Glucose has a molecular weight of $\var{glucose}$. How much does  $\var{0.25 * a}$ mole(s) of glucose weigh in grams?

Solution:

Putting our numbers into the formula we find that $\var{0.25 * a}$ mole(s) of glucose weighs

$\var{glucose} \times \var{0.25 * a} = \var{glucose * 0.25 * a}$ grams.

b)

Sodium chloride has a molecular weight of $\var{NaCl}$. How much does $\var{0.25 * b}$ mole(s) of sodium chloride weigh in grams?

Solution:

Putting our numbers into the formula we find that $\var{0.25 * b}$ mole(s) of sodium chloride weighs

$\var{NaCl} \times \var{0.25 * b} = \var{NaCl * 0.25 * b}$ grams.

To answer these questions we use the formula

$\dfrac{\text{mass of substance (in grams)}}{\text{molecular weight}} = \text{number of moles}$.

a)

Glucose has a molecular weight of $\var{glucose}$. How many moles of glucose are there in $\var{5 * a}$ grams?

Solution:

Putting our numbers into the formula we find that there are 

$\begin{align} \dfrac{\var{5 * a}}{\var{glucose}} &= \var{(5 * a) / glucose} \text{ moles}\\ &= \var{precround(((5 * a) / glucose), 2)} \text{ moles to 2 d.p.} \end{align}$ 

in $\var{5 * a}$ grams of glucose.

b)

Sodium chloride has a molecular weight of $\var{NaCl}$. How many moles of sodium chloride are there in $\var{5 * b}$ grams?

Solution:

Putting our numbers into the formula we find that there are

$\begin{align}\dfrac{\var{5 * b}}{\var{NaCl}} &= \var{(5 * b) / NaCl} \text{ moles} \\ & = \var{precround(((5 * b) / NaCl), 2)} \text{ moles to 2 d.p.} \end{align}$.

in $\var{5 * b}$ grams of sodium chloride.