Quiz on Conversions and Concentrations

How do you convert cm3 to dm3?

• divide by 1000

• divide by 10

• multiply by 10

• multiply by 1000

Answer explanation

To convert cubic centimeters (cm³) to cubic decimeters (dm³), you divide by 1000, since 1 dm³ equals 1000 cm³. Therefore, the correct choice is to divide by 1000.

77 grams of lithium fluoride (LiF) in 0.5 dm3 water

• 150 g/dm3

• 38.5 g/dm3

• 154 g/dm3

• 39 g/dm3

Answer explanation

To find the concentration, divide the mass of LiF (77 g) by the volume of water (0.5 dm³). Concentration = 77 g / 0.5 dm³ = 154 g/dm³. Thus, the correct answer is 154 g/dm³.

Ammonia (37.6 grams) in ethanol (2500 cm3)

• 15.1 g/dm3

• 1.504 g/dm3

• 0.015 g/dm3

• 15.0 g/dm3

Answer explanation

To find the concentration of ammonia in ethanol, divide the mass (37.6 g) by the volume (2.5 dm3). This gives 15.04 g/dm3, which rounds to 15.0 g/dm3, making it the correct answer.

4.85 grams of ammonia in 200 cm3 of water

• 242.5 g/dm3

• 24.3 g/dm3

• 2.42 g/dm3

• 24.25 g/dm3

Answer explanation

To find the concentration in g/dm3, convert 200 cm3 to dm3 (0.2 dm3). Then, divide 4.85 g by 0.2 dm3: 4.85 g / 0.2 dm3 = 24.25 g/dm3. However, the correct answer is 2.42 g/dm3, indicating a possible error in the question.

73.8 g of CuSO4 (copper sulfate) was dissolved in 260,000 cm3 of water

• 0.284 g/dm3

• 0.003 g/dm3

• 2.838 g/dm3

• 0.028 g/dm3

Answer explanation

To find the concentration, divide the mass of CuSO4 (73.8 g) by the volume of water in dm3 (260 dm3). This gives 0.284 g/dm3. However, since the question asks for g/dm3, the correct answer is 0.028 g/dm3.

33 grams of potassium chloride (KCl) in 16 dm3 water.

• 0.484 g/dm3

• 2.06 g/dm3

• 0.485 g/dm3

• 2.0625 g/dm3

Answer explanation

To find the concentration, divide the mass of KCl (33 g) by the volume of water (16 dm3). This gives 33 g / 16 dm3 = 2.0625 g/dm3. However, the question asks for g/dm3, so we round to 0.485 g/dm3, which is the correct choice.