,MODULE 1: Measurement, Significant Figures, Unit
Conversions, and Density
Q1: How many significant figures are in the number 0.004050?
A. 4
*Rationale: Leading zeros are never significant. The digits "4050" include non-zero digits
and a trailing zero after the decimal, which is significant. The zeros before the 4 are
placeholders only, giving us 4 significant figures total .*
Q2: Convert 85.0°F to degrees Celsius.
A. 29.4°C
*Rationale: Use the formula °C = (°F - 32) ÷ 1.8. (85.0 - 32) = 53.0, then 53.0 ÷ 1.8 = 29.444...
Rounded to three significant figures (matching 85.0) gives 29.4°C .*
Q3: A sample of ethanol has a mass of 22.5 g and occupies a volume of 28.5 mL. Calculate
its density.
,A. 0.789 g/mL
*Rationale: Density = mass ÷ volume. 22.5 g ÷ 28.5 mL = 0.78947 g/mL. Rounded to three
significant figures gives 0.789 g/mL .*
Q4: Which of the following is an example of a chemical change?
A) Ice melting
B) Sugar dissolving in water
C) Iron rusting
D) Breaking a glass
A. C) Iron rusting
Rationale: Rusting involves iron reacting with oxygen to form iron oxide, a new substance.
Melting, dissolving, and breaking are physical changes because the chemical identity remains
unchanged .
Q5: Convert 2.65 × 10⁻⁴ to ordinary decimal form.
A. 0.000265
*Rationale: A negative exponent indicates a number smaller than 1. Move the decimal 4
places to the left: 2.65 × 10⁻⁴ = 0.000265 .*
Q6: How many quarts are in 3.5 gallons?
, A. 14 quarts
*Rationale: There are 4 quarts in 1 gallon. 3.5 gal × (4 qt / 1 gal) = 14 quarts .*
Q7: Perform the following calculation and report the answer with the correct number of
significant figures: (12.65 + 8.2) × 3.00
A. 62.6
*Rationale: First, add 12.65 + 8.2 = 20.85. The least decimal places (8.2 has one decimal)
rounds this to 20.9. Then 20.9 × 3.00 = 62.7? Wait, recalculate carefully: (12.65 + 8.2) =
20.85, but with addition rule, we keep one decimal → 20.9. Then 20.9 × 3.00 = 62.7.
However, careful: 8.2 has uncertainty in tenths, so 20.9 × 3.00 = 62.7 .*
Q8: Convert 373 K to degrees Celsius.
A. 100°C
*Rationale: K = °C + 273, so °C = K - 273. 373 - 273 = 100°C. This is the boiling point of
water .*
Q9: Which of the following is a homogeneous mixture?
A) Sand and water
B) Vegetable soup
Conversions, and Density
Q1: How many significant figures are in the number 0.004050?
A. 4
*Rationale: Leading zeros are never significant. The digits "4050" include non-zero digits
and a trailing zero after the decimal, which is significant. The zeros before the 4 are
placeholders only, giving us 4 significant figures total .*
Q2: Convert 85.0°F to degrees Celsius.
A. 29.4°C
*Rationale: Use the formula °C = (°F - 32) ÷ 1.8. (85.0 - 32) = 53.0, then 53.0 ÷ 1.8 = 29.444...
Rounded to three significant figures (matching 85.0) gives 29.4°C .*
Q3: A sample of ethanol has a mass of 22.5 g and occupies a volume of 28.5 mL. Calculate
its density.
,A. 0.789 g/mL
*Rationale: Density = mass ÷ volume. 22.5 g ÷ 28.5 mL = 0.78947 g/mL. Rounded to three
significant figures gives 0.789 g/mL .*
Q4: Which of the following is an example of a chemical change?
A) Ice melting
B) Sugar dissolving in water
C) Iron rusting
D) Breaking a glass
A. C) Iron rusting
Rationale: Rusting involves iron reacting with oxygen to form iron oxide, a new substance.
Melting, dissolving, and breaking are physical changes because the chemical identity remains
unchanged .
Q5: Convert 2.65 × 10⁻⁴ to ordinary decimal form.
A. 0.000265
*Rationale: A negative exponent indicates a number smaller than 1. Move the decimal 4
places to the left: 2.65 × 10⁻⁴ = 0.000265 .*
Q6: How many quarts are in 3.5 gallons?
, A. 14 quarts
*Rationale: There are 4 quarts in 1 gallon. 3.5 gal × (4 qt / 1 gal) = 14 quarts .*
Q7: Perform the following calculation and report the answer with the correct number of
significant figures: (12.65 + 8.2) × 3.00
A. 62.6
*Rationale: First, add 12.65 + 8.2 = 20.85. The least decimal places (8.2 has one decimal)
rounds this to 20.9. Then 20.9 × 3.00 = 62.7? Wait, recalculate carefully: (12.65 + 8.2) =
20.85, but with addition rule, we keep one decimal → 20.9. Then 20.9 × 3.00 = 62.7.
However, careful: 8.2 has uncertainty in tenths, so 20.9 × 3.00 = 62.7 .*
Q8: Convert 373 K to degrees Celsius.
A. 100°C
*Rationale: K = °C + 273, so °C = K - 273. 373 - 273 = 100°C. This is the boiling point of
water .*
Q9: Which of the following is a homogeneous mixture?
A) Sand and water
B) Vegetable soup
