Here are the solutions with computations:

1. Convert kilometers to miles

$1 \text{ km} = 0.621371 \text{ miles}$ $27.0 \times 0.621371 = 16.776999$ Final Answer: 16.78 miles

---

2. Convert density of propane to kg/m³

$1 \text{ lb} = 0.453592 \text{ kg}, \quad 1 \text{ ft}^3 = 0.0283168 \text{ m}^3$ $\frac{36.28 \times 0.453592}{0.0283168}$ $= \frac{16.455}{0.0283168} = 581.3$ Final Answer: 581.30 kg/m³

---

3. Significant Figures in 685.602

• All nonzero digits are significant.
• Any zeros between significant figures are counted.
• Trailing zeros after a decimal point are significant.
  Answer: 6 significant figures

---

4. Convert meters to inches

$1 \text{ m} = 39.3701 \text{ inches}$ $0.525 \times 39.3701 = 20.6693$ Final Answer: 20.67 inches

---

5. Density in g/mL

$\text{Density} = \frac{\text{Mass}}{\text{Volume}}$ $\frac{0.23 \text{ kg} \times 1000 \text{ g/kg}}{250 \text{ mL}}$ $= \frac{230}{250} = 0.92$ Final Answer: 0.92 g/mL

---

6. Mass of Carbon Tetrachloride Sample

$\text{Mass} = \text{Density} \times \text{Volume}$ $0.793 \times 9.29 = 7.36997$ Final Answer: 7.37 g

---

7. Density of a Substance in g/mL

$\text{Density} = \frac{\text{Mass}}{\text{Volume}}$ $\frac{0.987 \times 1000}{4.52 \times 10^2}$ $= \frac{987}{452} = 2.18$ Final Answer: 2.18 g/mL

---

8. Convert meters to kilometers

$1 \text{ m} = 0.001 \text{ km}$ $2.88 \times 0.001 = 0.00288$ Final Answer: 0.00288 km

---

9. Convert kilograms to pounds

$1 \text{ kg} = 2.20462 \text{ lb}$ $2.00 \times 2.20462 = 4.40924$ Final Answer: 4.41 lb

---

10. Convert Celsius to Fahrenheit

$F = \frac{9}{5}C + 32$ $= \frac{9}{5} (30.0) + 32$ $= 54 + 32 = 86$ Final Answer: 86.00°F

---

Would you like further clarifications? Here are five related questions to deepen understanding:

1. How do significant figures affect the precision of calculations?
2. Why do different materials have different densities?
3. What is the relationship between mass, volume, and density?
4. How do you convert between different temperature scales (Kelvin, Celsius, Fahrenheit)?
5. Why is unit conversion important in scientific measurements?

Tip: Always check unit consistency when performing conversions to avoid miscalculations. 🚀