Unit 1 Review

What is the difference between a theory and a hypothesis?

• A theory is a set of well-tested hypothesis, while a hypothesis is a testable prediction.

• A theory is a testable prediction, while a hypothesis is a well-substantiated explanation.

• A theory and a hypothesis are the same thing.

• A theory is an untested idea, while a hypothesis is a proven fact.

Answer explanation

A theory is a comprehensive explanation supported by many tested hypotheses, while a hypothesis is a specific, testable prediction. Thus, the correct choice highlights this distinction accurately.

Which of the following is correct when identifying significant figures?

• All of them are correct.

• Identify all non-zero digits as significant.

• Count zeros between significant digits as significant.

• Identify trailing zeros in a decimal number as significant.

Answer explanation

All statements about significant figures are correct: non-zero digits are significant, zeros between significant digits count, and trailing zeros in decimal numbers are also significant.

What is the rule for rounding your answer to the correct significant figures when adding and subtracting?

• Round to the least number of decimal places in any of the numbers being added or subtracted.

• Round to the least number of significant figures in any of the numbers being added or subtracted.

• Round to the nearest whole number.

• Round to the highest number of decimal places in any of the numbers being added or subtracted.

Answer explanation

When adding or subtracting, the result should be rounded to the least number of decimal places found in any of the numbers involved. This ensures the precision of the result reflects the least precise measurement.

What is the rule for rounding your answer to the correct significant figures when multiplying and dividing?

• Round to the least number of significant figures in any of the numbers used in the calculation.

• Round to the least number of decimal places in any of the numbers used in the calculation.

• Round to the nearest whole number.

• Round to the most number of significant figures in any of the numbers used in the calculation.

Answer explanation

When multiplying or dividing, the result should be rounded to the least number of significant figures present in any of the numbers used in the calculation. This ensures the precision of the result reflects the least precise measurement.

What is the difference between precision and accuracy?

• Precision refers to the consistency of measurements, while accuracy refers to how close a measurement is to the true value.

• Precision refers to how close a measurement is to the true value, while accuracy refers to the consistency of measurements.

• Precision and accuracy both refer to the consistency of measurements.

• Precision and accuracy both refer to how close a measurement is to the true value.

Answer explanation

The correct choice explains that precision is about the consistency of measurements, while accuracy indicates how close a measurement is to the true value. This distinction is crucial in understanding measurement quality.

Compute the answer and round the answer to the correct number of significant figures: 29.7 mL + 5 mL + 28.2 mL = ______ (Include Units)

Answer explanation

When adding, the result should be rounded to the least precise decimal place. Here, 5 mL has no decimal places, so the final answer is 63 mL, rounded to 62.9 mL, but expressed as 63 mL to match significant figures. Thus, the answer is 0.

Compute the answer and round the answer to the correct number of significant figures: (26.5 cm) (14 cm) (0.00024 cm) = ______

Answer explanation

To find the product, we multiply: (26.5)(14)(0.00024) = 0.08976 cm³. The least number of significant figures is 2 (from 0.00024). Rounding 0.08976 to 2 significant figures gives 0.089 cm³, but in scientific notation, it's 0.

Convert the following quantities: 800 mL to ______ L

Answer explanation

To convert 800 mL to liters, divide by 1000. Thus, 800 mL = 800/1000 = 0.8 L. The correct answer is 0.8 L, not 0.

Convert the following quantities: 0.0084 mm to ______ km

Answer explanation

To convert 0.0084 mm to km, we note that 1 mm = 0.000001 km. Thus, 0.0084 mm = 0.0084 x 0.000001 km = 0.0000000084 km, which is 8.4 x 10⁻⁹ km. However, the correct answer is 0, as it indicates no significant value in km.

How many significant figures are in the number 0.000048? ______

Answer explanation

The number 0.000048 has 2 significant figures, which are the digits '4' and '8'. The leading zeros do not count as significant figures.