Question 1

Which of the following prefixes represents a multiplier of $$10^{-6}$$?

Accepted Answer

micro

Question 2

What is the SI base unit for measuring mass?

Accepted Answer

kilogram

Question 3

A sample contains $$6.022 	imes 10$$^{23}$$ molecules of water. What is the mass of this sample in grams? (Molar mass of water = 18.02$ g/mol)

Accepted Answer

$$18.02 g$$

Question 4

Which of the following numbers has 4 significant figures?

Accepted Answer

0.004560

Question 5

A lake has a surface area of $$100 mi$^2$$ and an average depth of $$20 ft. If $$the lake is polluted with $$0.4$$ 	extmu g Hg/mL, what is the total mass of mercury in kg in the lake? (1 mi$$^2$$ = $$2.59 	imes 10^6$ m^2$, 1 ft = 0.3048$ m, 1 mL = 1$$ 	imes $$10^{-3} L$$, 1 L = $$1 	imes 10$$^{-3}$$ m^3$)

Accepted Answer

$$2.98 	imes 10^2$ kg

Question 6

Which statement best describes the difference between accuracy and precision?

Accepted Answer

Accuracy is how close measurements are to the true value; precision is how close measurements are to each other.

Question 7

A student measures the mass of a sample as $$24.1 g $$and multiplies it by $$300. $$How many significant figures should the answer have?

Accepted Answer

1

Question 8

Which of the following is an example of a defined conversion with infinite significant figures?

Accepted Answer

$$1$$ inch = $$2.54 cm$$

Question 9

Calculate the percent by mass of nitrogen in ammonium nitrate, $$NH_4NO_3. ($$Molar mass: N = $$14.01 g/$$mol, H = $$1.01 g/$$mol, O = $$16.00 g/$$mol)

Accepted Answer

$$35.00\%$$

Question 10

A sample contains $$9.541 	imes 10$$^{21}$$ atoms of oxygen. How many mg of Cr_2$(CO_3$)_3$$ must there be? (Molar mass of $$Cr_2$$($$CO_3)_3$ = 284.02$ g/mol)

Accepted Answer

$$4.50 mg$$

Question 11

Which of the following is the correct empirical formula for benzene ($$C_6H_6$$)?

Accepted Answer

$$CH$$

Question 12

A student adds $$73.64$$ and $$1.5$$ and $$71.8. $$What is the correct answer with the proper number of significant figures?

Accepted Answer

$$147$$

Question 13

Which of the following best explains why the atomic mass of Fe on the periodic table is not exactly $$56.9354 g/$$mol?

Accepted Answer

It is a weighted average of the masses of all naturally occurring isotopes.

Question 14

Which of the following conversions is correct for $$0.0000071 sec $$using scientific notation?

Accepted Answer

$$7.1 	imes 10$$^{-6}$$ s

Question 15

If a bundle of No. 2 pencils weighs $$27,950 g $$and each pencil weighs $$5.6 g$$, how many pencils are in the bundle?

Accepted Answer

$$5,000$$

Question 16

Which of the following is the correct molar mass for $$CCl_2F_2$$?

Accepted Answer

$$120.91 g/$$mol

Question 17

Which of the following statements about significant figures is FALSE?

Accepted Answer

All zeros in any number are always significant.

Question 18

A blood sample analyzed in four labs gives the following cholesterol results: 100, 175, 200, 125 mg/dL (average = 150). Is this set of results accurate, precise, both, or neither?

Accepted Answer

Neither accurate nor precise

Question 19

Which of the following is the correct percent composition of phosphorus in $$P_2O_5$$? (Molar mass: P = $$30.97 g/$$mol, O = $$16.00 g/$$mol)

Accepted Answer

$$43.64\%$$

General Chemistry Study Notes: Measurement, Units, Moles, and Chemical Formulas

Guida di studio - Domande di pratica

Study guide - Flashcard