Exam 1 Chem 1100 Fall 2003 Dr. Byrd

MULTIPLE CHOICE. Choose the answer that best completes the statement or answers the

question. Each correct answer is worth 2.5 points each. (2 sig figs)

1) Bromine belongs to the ________ group of the periodic table.

A) alkali metal

B) noble gas

C) halogen

D) alkaline earth metal

E) none of the above

2) Which of the following elements is classified as a semimetal?

A) calcium

B) fluorine

C) germanium

D) uranium

E) all of them are semimetals

3) Convert 0.003002 to standard scientific notation.

A) 3.002 x 10³

B) 3.002 x 10^-3

C) 3002 x 10⁶

D) 3002 x 10^-6

E) 3.00 x 10³

4) The average distance between nitrogen and oxygen atoms is 115 pm in a compound called nitrogen dioxide. What is this distance in centimeters?

A) 1.15 x 10^-9 cm

B) 1.15 x 10^-7 cm

C) 1.15 x 10¹⁶ cm

D) 1.15 x 10¹² cm

E) 1.15 x 10^-8 cm

5) If the melting point of titanium metal is 1672 °C, what is its melting point in Kelvins?

A) 1399 K

B) 3042 K

C) 897 K

D) 1945 K

E) none of the above

6) Which of the following statements does not describe a physical property of chlorine?

A) Chlorine combines with sodium to form table salt.

B) The freezing point of chlorine is –101 °C.

C) The density of chlorine gas at standard temperature and pressure is 3.17 g/L.

D) The color of chorine gas is green.

E) all of the above

7) Which of the following numbers has the greatest number of significant figures?

A) 418000

B) 0.5070

C) 0.201

D) 6.02 x 10²⁴

E) both b} and c}

8) How many significant figures are there in the answer to the following problem?

(8.881 x 2.100) + 0.590 = ?

A) one

B) two

C) three

D) four

E) five

9) The LD₅₀ values for several chemicals are listed below. These chemicals were tested on laboratory mice. Which was the most toxic to the mice?

A) ethyl alcohol, 10.6 g/kg

B) chloroform, 3.2 g/kg

C) sodium cyclamate, 17 g/kg

D) aspirin 1.5 g/kg

10) To the correct number of significant figures, what is the temperature reading on the following Celsius thermometer?

A) 15.7 °C

B) 15.6 °C

C) 15 °C

D) 16 °C

E) 15.67 °C

11) A sample of pure lithium carbonate contains 18.8% lithium by mass. What is the % lithium by mass in a sample of pure lithium carbonate that has twice the mass of the first sample?

A) 37.6%

B) 18.8%

C) 75.2%

D) 9.40%

12) How many protons (p) and neutrons (n) are in an atom of Sr-90?

A) 38 p, 52 n

B) 90 p, 38 n

C) 52 p, 38 n

D) 38 p, 90 n

E) none of these are correct

13) In which of the following sets do all species have the same number of electrons?

A) O, O^2-, O²⁺

B) Br^-2, Kr, Sr¹⁺

C) Mg²⁺, Sr²⁺, Ba²⁺

D) C, N^3-, O^2-

E) Br^-, Kr, Sr²⁺

14) What type of bonding is found in the compound PCl₅?

A) ionic bonding

B) covalent bonding

C) hydrogen bonding

D) metallic bonding

E) acid bonding

15) Which of the compounds, C₃H₈, MgCl₂, Zn(NO₃)₂, OCl₂, are expected to exist as molecules?

A) C₃H₈, Zn(NO₃)₂, and OCl₂

B) MgCl₂ and Zn(NO₃)₂

C) only C₃H₈

D) C₃H₈ and OCl₂

E) all of them

16) The solid compound, sodium carbonate_, contains

A) Na⁺, C⁴⁺, and O^2- ions.

B) Na₂⁺ and CO₃^2- ions.

C) Na₂CO₃ molecules.

D) Na⁺ ions and CO₃^2-ions.

E) SO⁺² and CO^-1

17) When dissolved in water, of HClO_4, Ca(OH)₂, KOH, NaCl, HI, which are acids?

A) NaCl and HI

B) only HI

C) Ca(OH)₂ and KOH

D) only KOH

E) HClO₄ and HI

18) Li₂S is named

A) lithium sulfide.

B) lithium sulfur.

C) lithium(II) sulfide.

D) lithium disulfide.

E) sulfurium lithide

19) The formula for dinitrogen trioxide is

A) N₂O_3.

B) N(OH)_3.

C) N₃O_2.

D) (NO₃)_2.

E) none of the above

20) The compound, Cu(ClO₃)₂, is named

A) copper chlorate(II).

B) copper(II) perchlorate.

C) copper(I) chlorate(II).

D) copper(I) chlorate.

E) copper(II) chlorate.

21) The formula of potassium dihydrogen phosphate is

A) PoH₂PO₄

B) KH₂PO₃

C) KH₂PO₄

D) K₃H₂PO₄

E) K₂H₂PO₄

22) What is the stoichiometric coefficient for oxygen when the following equation is balanced using the lowest, whole-number coefficients

________ C₃H₈O(l) + ________ O₂(g) Â ________ CO₂(g) + ________ H₂O(l)

A) 9

B) 5

C) 3

D) 7

E) 4

23) What is the molar mass of hydrogen gas?

A) 6.02 x 10²³ g/mol

B) 2.02 g/mol

C) 1.01 g/mol

D) 1.20 x 10²³ g/mol

E) none of the above

24) Which of the following has the greatest mass?

A) 0.500 mol of O₂

B) 16.0 g of O₂

C) 6.02 x 10²³ molecules of O₂

D) 3.01 x 10²³ molecules of O₂

E) All of the above have the same mass

PROBLEMS. Be sure to show your work to earn credit. Don't forget units and significant figures.

25) (12) A piece of metal ore weighs 8.25 g. When a student places it into a graduated cylinder containing water, the liquid level rises from 21.25 mL to 26.47 mL. What is the density of the ore?

26) (12) An element has three naturally occurring isotopes. One has an abundance of 37.4% and an isotopic mass of 184.953 amu; the second has an abundance of 42.6% and a mass of 186.956 amu, and the third has an abundance of 20.0% and a mass of 188.955 amu. What is the atomic weight of the element?

27) Iron(III) oxide reacts with carbon monoxide to form pure iron metal and carbon dioxide.

a) (6) Write the balanced chemical equation for this reaction.

b) (10) Using your balanced chemical equation, calculate the number of grams of pure iron that can be prepared from 1.00 x 10² g of iron(III) oxide and an excess of carbon monoxide.