60 i believe i haven't did science in a while sorry if im wrong though... ._.
The density of the stone is 5 g/cm³.
Mass = 25 g
Volume = 7 mL – 2 mL = 5 mL = 5 cm³
Density = mass/volume = 25 g/5 cm³ = 5 g/cm³
Answer:
1.36 × 10³ mL of water.
Explanation:
We can utilize the dilution equation. Recall that:

Where <em>M</em> represents molarity and <em>V</em> represents volume.
Let the initial concentration and unknown volume be <em>M</em>₁ and <em>V</em>₁, respectively. Let the final concentration and required volume be <em>M</em>₂ and <em>V</em>₂, respectively. Solve for <em>V</em>₁:

Therefore, we can begin with 0.640 L of the 2.50 M solution and add enough distilled water to dilute the solution to 2.00 L. The required amount of water is thus:

Convert this value to mL:

Therefore, about 1.36 × 10³ mL of water need to be added to the 2.50 M solution.
I don't know which ones r, could u add options, maybe?
Answer:a) 0.1 mole. b) 4g. c) 2% d) 196 mL
Explanation: in 200mL , 0.1mole
mw NaOH = 40g/mol —> 4g in 0.1 mole
4g in 200mL so 2g in 100mL
density NaOH = 1g/mL so if 4g in 200 mL, 4mL , 196 mL water