Using Scientific Measurements

A chemical reaction was carried out three times. The mass of the product was 8.93 g for the first trial, 8.94 g for the second trial, and 8.92 g for the third trial. Under the conditions of the experiment, the reaction is known to yield 8.60 g of product. The three mass values measured are

• accurate.

• precise, but not accurate.

• both accurate and precise.

• neither accurate nor precise.

For numbers less than 0.1, such as 0.06, the zeros to the right of the decimal point but before the first nonzero digit

• are not significant.

• show the decimal place of the first digit.

• show that the zero on the left side of the decimal is not significant.

• are always uncertain.

The number of significant figures in the measurement 0.000 305 kg is

• 2

• 3

• 6

• 7

Written in scientific notation, the measurement 0.000 065 cm is

• 65 x 10^-4 cm

• 6.5 x 10^-5 cm

• 6.5 x 10^-6 cm

• 6.5 x 10^-4 cm

When the difference between a measured value and the known value is expressed as percentage error, it is usually written as

• a positive number.

• a negative number.

• both positive and negative.

• either a negative number or a positive number.

A measurement is accurate if it

• is reproducible.

• is close to the true value.

• has many decimal places.

• has many significant figures.

To determine the number of significant digits in a measurement, follow the rule that

• all zeros are significant.

• all nonzero digits are significant.

• zeros between digits are not significant.

• final digits less than 5 are not significant.

The measurement 0.0255 g, rounded off to two significant figures, would be

• 0.02 g.

• 0.025 g.

• 0.026 g.

• 2.5 x 10² g

What is 1 x 10² divided by 1 x 10^-3?

• 1 x 10^-6

• 1 x 10^-1

• 1 x 10^2/3

• 1 x 10⁵

What is the sum of 100.0 g and 0.01 g, expressed in scientific notation and written with the correct number of significant figures

• 10 001 x 10^-2 g

• 1.0 x 10² g

• 1.000 x 10² g

• 1.00 ´ 10² g