Answer:
The answer is 10 g/mL
Step-by-step explanation:
The density of a substance can be found by using the formula
![density = (mass)/(volume) \\](https://img.qammunity.org/2021/formulas/chemistry/college/2qztd1zu9lpwav17leag2cjjn695yipoje.png)
From the question
mass = 300 g
volume = final volume of water - initial volume of water
volume = 40 - 10 = 30 mL
We have
![density = (300)/(30) = (30)/(3) \\](https://img.qammunity.org/2021/formulas/chemistry/high-school/s2j81prit29myb7947egmoxg02vlxt00do.png)
We have the final answer as
10 g/mL
Hope this helps you