Self Assessment B


1	Which of the following is true about the scientific method?
		A)	A hypothesis is a set of observations that are explained by an experiment.
		B)	Researchers design experiments to prove the conclusions they have already reached.
		C)	The purpose of performing an experiment is to confirm or contradict a hypothesis.
		D)	To be useful, data must be qualitative.
		E)	Quantitative data are usually in the form of descriptive observations.


2	Which of the following is not an example of a mixture?
		A)	iced tea
		B)	distilled water
		C)	mashed potatoes
		D)	vegetable soup
		E)	tomato juice


3	A 9.4-g sample of powered titanium was added to a graduated cylinder originally containing 6.8 mL of water. After addition of the titanium, the water level in the graduated cylinder was 8.9 mL. What is the density of titanium?
		A)	1.4 g/cm³
		B)	4.5 g/cm³
		C)	1.1 g/cm³
		D)	0.22 g/cm³


4	At one atmosphere pressure, mercury solidifies at -38.0 ^oF. Express this temperature in degrees Celcius and Kelvin.
		A)	-126 ^oC and 147 K
		B)	-39 ^oC and 234 K
		C)	-21 ^oC and 252 K
		D)	39 ^oC and 312 K
		E)	-68 ^oC and 205 K


5	How many significant figures are there in the number 0.0203610 g?
		A)	8
		B)	7
		C)	6
		D)	5


6	A sample of a liquid has a density of 2.1 g/mL. What volume of the liquid has a mass of 4.242 g?
		A)	8.9 mL
		B)	2.0 mL
		C)	2.02 mL
		D)	2.020 mL
		E)	0.50 mL


7	A laboratory technician analyzed a sample three times for percent iron and got the following results: 22.43% Fe, 24.98% Fe, and 21.02% Fe. The actual percent iron in the sample was 22.81%. The analyst's
		A)	precision was poor but the average result was accurate.
		B)	accuracy was poor but the precision was good.
		C)	work was only qualitative.
		D)	work was precise.
		E)	C and D.


8	The density of magnesium is 1.7 g/cm³, and the density of iron is 7.9 g/cm³. Consider a block of iron with a mass of 819 g. What is the mass of a block of magnesium that has the same volume as the block of iron?
		A)	1.8 x 10² g
		B)	61 g
		C)	2.8 x 10³ g
		D)	3.8 x 10³ g
		E)	None of the above.


9	The recommended daily allowance (RDA) of calcium is 1200 mg. Calcium carbonate contains 12% calcium by mass. How many grams of calcium carbonate are needed to provide the RDA of calcium?
		A)	1.3 g
		B)	1.4 g
		C)	0.14 g
		D)	10 g
		E)	0.19 g


10	Table salt (sodium chloride) is 42.7% sodium. How many grams of salt contain 76.0 g of sodium?
		A)	32.5 g
		B)	178 g
		C)	3.25 x 10³ g
		D)	1.78 g
		E)	1.78 x 10⁴ g

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