Answers to true false pretest on Measurements in Chemistry

1. Every measurement has a unit tied to it. true, This applies to all measured numbers.

2. Physical quantities are properties that can be measured. true, Quantities that can be measured are physically observable.

3. The prefix milli- in the metric system means 1/100 . false, milli- is the same as a factor of 1/1000 or 0.001 or 1 x 10-3

4. The Celsius degree is larger than the Kelvin degree. true, this is why we can convert from Celsius to Kelvin by adding 273.15

5. The melting point for water is 0oC or 273 Kelvin. true, The melting point for water is used to define 0o Celsius

6. The prefix micro- in the metric system equals 1/1,000 . false, micro- is the same as 1/1,000,000 or 0.000001 or 1 x 10-6

7. The mass of an object changes when it is moved. false, the amount of matter in anobject doesn't change with position

8. A kilogram is smaller than a pound. false, the kilogram is larger than a pound. 1 kilogram = 2.2 pounds

9. A length unit in the metric system is the liter. false, length is measured in terms of meters. The liter is a volume unit.

10. The number 54.07 grams has two significant figures. false, this number must have "4" significant figures.

11. The number 41.526 +/- 0.0001 has five significant figures. true, the "6" or last digit is the uncertain one

12. Exact numbers have an infinite number of significant figures. true, all definitions and counts have no uncertain digits

13. Rounding off 34.79 meters to one decimal place gives 34.8 m. true, increase the preceding number by one when you round off a greater than or equal to "5".

14. Multiplying 1.3 x 103 by 3.0 x 104 gives 3.9 x 107. true, multiply the coefficients, 1.3 x 3.0 and add the powers of ten

15. There are 60 seconds in a minute, so in 4 minutes there are 2400 seconds. false, there are 240 s = 4 minutes x (60 s / minute)

16. The relation o F = (1.8oF/ 1oC) x o C + 32 means 50oC equals 122 oF true, o F = 1.8 x 50 + 32 = 90 + 32 = 122o F

17. A calorie will raise the temperature of one g of water by 1 o C. true, this is one way the "small" calorie is defined.

18. Metals have large specific heats, that is why they conduct heat well. false, Metals have very low specific heats. they warm up quickly and conduct heat well because metals require little energy to get warm.

19.Density is a property that depends on the size of an object. false, the density of a material is the same no matter how little or how much you have of it. Density is an "intensive" property. It is independent of amount.

20. Specific gravity has no units. true, specific gravity is defined as the ratio of the density of a substance to the denisty of water at the same temperature. The units all cancel.

Revised June 29, 2013 all rights reserved Dr. Walt Volland