Example (1): Density of petrol is 0.8g/cm³
and density of mercury is 13.6g/cm³.
a) What volume of petrol has the same
mass as 5cm³ of mercury?
b) What mass of petrol has the same
volume as 41g of mercury?
Answer:



Answer :

Certainly! Let's solve each part of the question step-by-step.

### Part (a): Calculating the volume of petrol that has the same mass as 5 cm³ of mercury

1. Determine the mass of 5 cm³ of mercury:
- Density of mercury is 13.6 g/cm³.
- Volume of mercury is 5 cm³.
- Using the formula [tex]\( \text{mass} = \text{volume} \times \text{density} \)[/tex],
[tex]\[ \text{mass}_{\text{mercury}} = 5 \, \text{cm}^3 \times 13.6 \, \text{g/cm}^3 = 68 \, \text{g} \][/tex]

2. Find the volume of petrol that has the same mass:
- Density of petrol is 0.8 g/cm³.
- Mass of petrol is the same as the mass of mercury, which is 68 g.
- Using the formula [tex]\( \text{volume} = \frac{\text{mass}}{\text{density}} \)[/tex],
[tex]\[ \text{volume}_{\text{petrol}} = \frac{68 \, \text{g}}{0.8 \, \text{g/cm}^3} = 85 \, \text{cm}^3 \][/tex]

So, the volume of petrol that has the same mass as 5 cm³ of mercury is 85 cm³.

### Part (b): Calculating the mass of petrol that has the same volume as 41 g of mercury

1. Determine the volume of 41 g of mercury:
- Density of mercury is 13.6 g/cm³.
- Mass of mercury is 41 g.
- Using the formula [tex]\( \text{volume} = \frac{\text{mass}}{\text{density}} \)[/tex],
[tex]\[ \text{volume}_{\text{mercury}} = \frac{41 \, \text{g}}{13.6 \, \text{g/cm}^3} \approx 3.015 \, \text{cm}^3 \][/tex]

2. Find the mass of petrol that has the same volume:
- Density of petrol is 0.8 g/cm³.
- Volume of petrol is the same as the volume of mercury, which is approximately 3.015 cm³.
- Using the formula [tex]\( \text{mass} = \text{volume} \times \text{density} \)[/tex],
[tex]\[ \text{mass}_{\text{petrol}} = 3.015 \, \text{cm}^3 \times 0.8 \, \text{g/cm}^3 \approx 2.412 \, \text{g} \][/tex]

So, the mass of petrol that has the same volume as 41 g of mercury is approximately 2.412 g.

To summarize the answers:
- The volume of petrol that has the same mass as 5 cm³ of mercury is 85 cm³.
- The mass of petrol that has the same volume as 41 g of mercury is approximately 2.412 g.

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