Answer
2.5%
Explanation
The percentage by mass of a solution can be calculated by dividing the mass of the solute by the mass of the solvent, then, multiplied by 100.
[tex]Percent\text{ }concentration=\frac{Mass\text{ }of\text{ }solute}{Mass\text{ }of\text{ }solution}\times100[/tex]According to this question, 25 grams of dextrose is dissolved in 1000 grams of solution. The percent concentration is calculated as follows:
[tex]Percent\text{ }concentration=\frac{25g}{1000g}\times100=2.5\%[/tex]Therefore, If there are 25 grams of dextrose dissolved in 1000 g of solution, the percent concentration is 2.5%