I am getting ready for my first chemistry test but I need help solving these que

Question

I am getting ready for my first chemistry test but I need help solving these questions.

Thanks much,

1. When a solid substance with a mass of 6.0 g is placed into a graduated cylinder with 25 mL of water, the volume increases to 36 mL. What is the density of the unknown substance?

2. If the distance from Venus to the sun is 6.7 × 106 miles, and light travels at 3.0 × 108 meters/second, how many minutes does it take for light from the sun to reach Venus? (1.61 km = 1 mile)

3. If 2.54 cm = 1 in. and 36 in. = 1 yard, then 360 cm = (Answer in yards)

4. A nugget of gold with a mass of 521 g is added to 50.0 mL of water. The water level rises to a volume of 77.0 mL. What is the density of the gold?

4. A nugget of gold with a mass of 521 g is added to 50.0 mL of water. The water level rises to a volume of 77.0 mL. What is the density of the gold?

Explanation / Answer

1.

mass of solid = 6g

Volume occupied by solid = Final reading - Initial reading = 36 mL - 25 mL = 11 mL

density = mass / volume = 6 g / 11 mL = 0.545 g/mL

2.

distance = 6.7 x 10^6 miles

1 mile = 1.61 km

6.7 x 10^6 miles = 6.7 x 10^6 * 1.61 km = 1.08 x 10^7 km = 1.08 x 10^10 m ( 1 km = 1000 m)

speed of light = 3 x 10^8 m/s

time = distance / speed = 1.08 x 10^10 / 3 x 10^8 = 36 seconds

60 seconds = 1 minute

36 seconds = 1 * 36 / 60 = 0.6 minutes

3.

2.54 cm = 1 inch

1 cm = 1 / 2.54 inch

360 cm = 360 / 2.54 = 141.73 inch

Now,

36 inch = 1 yard

1 inch = 1/36 yard

141.73 inch = 141.73 / 36 = 3.94 yards

4.

Mass of gold = 521 g

Volume occupied by gold = Final reading - Initial reading = 77 mL - 50 mL = 27 mL

Density of gold = Mass / Volume = 521 / 27 = 19.30 g/mL

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