To find the mass of the water, we can use the principle of conservation of mass. The total mass of the mixture is the sum of the masses of the individual components, which includes the mass of the water, salt, and iodine.
We know the following:
- Mass of salt = 5.0 grams
- Mass of iodine = 15.0 grams
- Total mass of the mixture = 225 grams
Let the mass of water be \( m_w \). According to the equation for conservation of mass, we have:
\[ m_w + \text{mass of salt} + \text{mass of iodine} = \text{total mass} \]
Substituting the values:
\[ m_w + 5.0 \text{ grams} + 15.0 \text{ grams} = 225 \text{ grams} \]
Now combine the masses of salt and iodine:
\[ m_w + 20.0 \text{ grams} = 225 \text{ grams} \]
Now, isolate \( m_w \):
\[ m_w = 225 \text{ grams} - 20.0 \text{ grams} \] \[ m_w = 205 \text{ grams} \]
Thus, the mass of the water is:
D. 205 grams