How many significant figures are in the following?

12

Which of the following are exact numbers? There are 100 cm in 1 m.

Which of the following are exact numbers?

The budget deficit of the U.S. government in fiscal year 1990 was 269 billion.

Which of the following are exact numbers?

In 1983,1759 Ph.D.s in chemistry were awarded in the United States.

Which of the following are exact numbers?

The announced attendance at a football game was 52,806.

Which of the following are exact numbers?

One yard is equal to 0.9144 m}$.

Which of the following are exact numbers?

The elevation of Breckenridge, Colorado, is 9600 ft$.

Why is the separation of mixtures into pure or relatively pure substances so important when performing a chemical analysis?

Distinguish between physical changes and chemical changes.

A student performed an analysis of a sample for its calcium content and got the following results:

$$14.92 \% \quad 14.91 \% \quad 14.88 \% \quad 14.91 \%$$

The actual amount of calcium in the sample is 15.70. What conclusion can you draw about the accuracy and precision of these results?

Use the following data to calculate the number of minutes in a month: 24 hours per day, 60 minutes per hour, 7 days per week, and 4 weeks per month.

There are 365 days per year, 24 hours per day, 12 months per year, and 60 minutes per hour. Use these data to determine how many minutes are in a month.

Which of the following statements (hypotheses) could be tested by quantitative measurement?

Rolaids consumes 47 times its weight in excess stomach

Gallium (Ga) consists of two naturally occurring isotopes with masses of 68.926 and 70.925 amu. The average atomic mass of Ga is 69.72 amu. Calculate the abundance of each isotope.