A.define the electron dot diagram.
b.use the electron dot diagram to represent 3 elements.
! : )

See explanation

Explanation:

We know that we obtain the w/v % concentration as follows;

w/v (%) = [mass solute (g) ÷ volume solution (mL)] × 100

volume of solution = 4.93 mL

So,

For dextromethorphan

0.25 = mass/4.93  * 100

0.25 * 4.93 = 100 mass

mass = 0.25 * 4.93/100

mass = 0.0123 g

For guaifenisin,

1.1 = mass/4.93 * 100

1.1 * 4.93 = 100 mass

mass = 1.1 * 4.93/100

mass = 0.0542g