EHS Honors Chemistry Quiz 1

1. How many significant figures are in 3.04?

2

3

1

What are significant figures?

The number 3.04 has three significant figures. Significant figures are the digits in a number that carry meaning in terms of precision. In this case, the digits 3, 0, and 4 are all significant because they contribute to the overall value of the number. The zero between the 3 and 4 is also significant because it is between two nonzero digits. Therefore, the correct answer is 3.

Explanation

The number 3.04 has three significant figures. Significant figures are the digits in a number that carry meaning in terms of precision. In this case, the digits 3, 0, and 4 are all significant because they contribute to the overall value of the number. The zero between the 3 and 4 is also significant because it is between two nonzero digits. Therefore, the correct answer is 3.

2. What is 3.22 x 10³ in long form?

.322

32.2

322

3220

The long form of 3.22 x 10^3 is 3220. In scientific notation, when a number is multiplied by 10 raised to a power, it indicates how many places the decimal point should be moved to the right. In this case, 3.22 is multiplied by 10^3, which means the decimal point should be moved three places to the right. So, the long form of 3.22 x 10^3 is 3220.

Explanation

The long form of 3.22 x 10^3 is 3220. In scientific notation, when a number is multiplied by 10 raised to a power, it indicates how many places the decimal point should be moved to the right. In this case, 3.22 is multiplied by 10^3, which means the decimal point should be moved three places to the right. So, the long form of 3.22 x 10^3 is 3220.

3. How many significant figures are in 0.00345

6

5

3

4

The number 0.00345 has three significant figures. Significant figures are the digits that carry meaning in a number. In this case, the digits 3, 4, and 5 are significant because they are not zero and they contribute to the overall value of the number. The leading zeros before the 3 are not significant because they only indicate the decimal point's position.

Explanation

The number 0.00345 has three significant figures. Significant figures are the digits that carry meaning in a number. In this case, the digits 3, 4, and 5 are significant because they are not zero and they contribute to the overall value of the number. The leading zeros before the 3 are not significant because they only indicate the decimal point's position.

4. A accepted measurement of a length of wood is 3.5 m. Your measurement of a piece of wood is 2.5 m. What is your percent error?

28.6%

71.4%

35%

25%

The percent error is calculated by taking the absolute difference between the accepted measurement and your measurement, dividing it by the accepted measurement, and then multiplying by 100. In this case, the absolute difference is 3.5 m - 2.5 m = 1 m. Dividing 1 m by 3.5 m and multiplying by 100 gives us a percent error of 28.6%.

Explanation

The percent error is calculated by taking the absolute difference between the accepted measurement and your measurement, dividing it by the accepted measurement, and then multiplying by 100. In this case, the absolute difference is 3.5 m - 2.5 m = 1 m. Dividing 1 m by 3.5 m and multiplying by 100 gives us a percent error of 28.6%.

5. Convert 402 m into Km.

.402 km

402000 km

4.02 Km

40.2 Km

To convert meters to kilometers, we divide the given value by 1000, since there are 1000 meters in one kilometer. Therefore, to convert 402 meters into kilometers, we divide 402 by 1000, resulting in 0.402 kilometers.

Explanation

To convert meters to kilometers, we divide the given value by 1000, since there are 1000 meters in one kilometer. Therefore, to convert 402 meters into kilometers, we divide 402 by 1000, resulting in 0.402 kilometers.

6. Convert 250 Km into mm.

.250 mm

.000000250 mm

25000mm

250000000 mm

To convert kilometers to millimeters, you need to multiply the given value by 1,000,000. Therefore, 250 kilometers is equal to 250,000,000 millimeters.

Explanation

To convert kilometers to millimeters, you need to multiply the given value by 1,000,000. Therefore, 250 kilometers is equal to 250,000,000 millimeters.

7. Mrs. McCarthy wants to test what the freezing point of a 1% salt water solution is. She fills a vial with 10 mL of tap water and another vial with 10 mL of the 1% salt water solution. She then puts it in the freezer with a thermometer in each vial. She records the temperature every 2 minutes until it freezes. What is the dependent variable in this experiment?

The thermometer

The time it takes for the salt water to freeze

The regular water

The types of water

The dependent variable in this experiment is the time it takes for the salt water to freeze. This is because the freezing time is being measured and recorded as the experiment progresses. The other options, such as the thermometer, regular water, and types of water, are not being specifically measured or recorded in this experiment.

Explanation

The dependent variable in this experiment is the time it takes for the salt water to freeze. This is because the freezing time is being measured and recorded as the experiment progresses. The other options, such as the thermometer, regular water, and types of water, are not being specifically measured or recorded in this experiment.

8. Using significant figures, what is the answer to the following problem?

3.46 x 6.2 x 4 x 5.035

432

400

430

432.04

The answer 400 is obtained by multiplying the given numbers 3.46, 6.2, 4, and 5.035 using significant figures. Since 4 has only one significant figure, it limits the result to one significant figure. Therefore, the answer is rounded to the nearest whole number, which is 400.

Explanation

The answer 400 is obtained by multiplying the given numbers 3.46, 6.2, 4, and 5.035 using significant figures. Since 4 has only one significant figure, it limits the result to one significant figure. Therefore, the answer is rounded to the nearest whole number, which is 400.

9. Mrs. McCarthy wants to test what the freezing point of a 1% salt water solution is. She fills a vial with 10 mL of tap water and another vial with 10 mL of the 1% salt water solution. She then puts it in the freezer with a thermometer in each vial. She records the temperature every 2 minutes until it freezes. What is the control in this experiment?

The thermometer

The time it took for the salt water to freeze

The regular tap water

The types of water

The control in this experiment is the regular tap water. The control is the standard against which the experimental group is compared. In this case, the regular tap water is used as a baseline to compare the freezing point of the 1% salt water solution. By comparing the freezing point of the salt water solution to the freezing point of the regular tap water, Mrs. McCarthy can determine the effect of the salt on the freezing point. The control ensures that any changes in the freezing point are due to the presence of salt and not other factors.

Explanation

The control in this experiment is the regular tap water. The control is the standard against which the experimental group is compared. In this case, the regular tap water is used as a baseline to compare the freezing point of the 1% salt water solution. By comparing the freezing point of the salt water solution to the freezing point of the regular tap water, Mrs. McCarthy can determine the effect of the salt on the freezing point. The control ensures that any changes in the freezing point are due to the presence of salt and not other factors.

10. Mrs. McCarthy wants to test what the freezing point of a 1% salt water solution is. She fills a vial with 10 mL of tap water and another vial with 10 mL of the 1% salt water solution. She then puts it in the freezer with a thermometer in each vial. She records the temperature every 2 minutes until it freezes. What is the independent variable in this experiment?

The thermometer

The time it took for the salt water to freeze

The regular water

The types of water

The independent variable in this experiment is the types of water. Mrs. McCarthy is testing the freezing point of different types of water - tap water and a 1% salt water solution. She is manipulating the types of water by filling one vial with tap water and another vial with the salt water solution. The independent variable is the factor that is being changed or manipulated in an experiment, and in this case, it is the types of water.

Explanation

The independent variable in this experiment is the types of water. Mrs. McCarthy is testing the freezing point of different types of water - tap water and a 1% salt water solution. She is manipulating the types of water by filling one vial with tap water and another vial with the salt water solution. The independent variable is the factor that is being changed or manipulated in an experiment, and in this case, it is the types of water.

Ehs Honors Chemistry Quiz 1