Question

1 from their density values, decide whether each of the following substances will sink or float when placed in sea water which has a density of 1.025 g/ml.
#1 - gasoline: 250 g in a volume of 285 ml
#2 - asphalt: 309 g in a volume of 250 ml
#3 - mercury: 519 g in a volume of 250 ml
#4 - cork: 99 g in a volume of 250 ml
which of these four substances will float in sea water?
a #1 and #3
b #2 and #4
c #2 and #3
d #1 and #4

Explanation:

Step1: Recall density formula

Density ($
ho$) is calculated as $
ho = \frac{\text{mass (m)}}{\text{volume (V)}}$. A substance floats in sea water if its density is less than 1.025 g/mL.

Step2: Calculate density of Gasoline (#1)

Mass = 250 g, Volume = 285 mL.
$
ho_{gasoline} = \frac{250}{285} \approx 0.877$ g/mL.
0.877 < 1.025, so it floats.

Step3: Calculate density of Asphalt (#2)

Mass = 309 g, Volume = 250 mL.
$
ho_{asphalt} = \frac{309}{250} = 1.236$ g/mL.
1.236 > 1.025, so it sinks.

Step4: Calculate density of Mercury (#3)

Mass = 519 g, Volume = 250 mL.
$
ho_{mercury} = \frac{519}{250} = 2.076$ g/mL.
2.076 > 1.025, so it sinks.

Step5: Calculate density of Cork (#4)

Mass = 99 g, Volume = 250 mL.
$
ho_{cork} = \frac{99}{250} = 0.396$ g/mL.
0.396 < 1.025, so it floats.

Step6: Identify floating substances

Gasoline (#1) and Cork (#4) have densities less than 1.025 g/mL, so they float. This matches option D.

Answer:

D. #1 and #4