CHEM 105N TEST QUESTIONS (1-11)

. covalent or ionic? CCl4

. covalent

The volume of a gas with a pressure of 1.2 atm increases from 1.0 L to 4.0 L. What is the final pressure of the gas, assuming no change in moles or temperature? Remember the correct number of significant figures and of course units.

.30 atm

A balloon that contains 0.500 L of helium at 25 °C is cooled to 11 °C, at a constant pressure. What volume does the balloon now occupy? Include the correct units.

.477 L

The half-life of bromine-74 is 25 min. How much of a 4.0 mg sample is still active after 75 min?

.50 mg

A patient's systolic pressure is measured as 128 mm Hg. What is this pressure in units of atm? 128 atm 1.28 atm 0.168 atm 9.73 x 104 atm 8.71 atm

0.168 atm

How many significant figures does each of these measurements have? 50 grams

1

Which metric relationship is correct? 1 milliliter = 1,000 liters 1,000,000 mg = 1 microgram 1,000 km = 1m 1 liter = 1,000,000 ml 1 cm = 10 mm

1 cm = 10 mm

A calculator answer of 1.03954 must be rounded off to four significant figures. What answer is reported?

1.040

How many valence electrons are in a molecule of formaldehyde (CH2O)?

12

Ca2+ has 20 protons and ___ total electrons.

18

What is the full, ground-state electronic configuration for a neutral atom of Ge? 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2 1s2 2s2 2p6 3s2 3p6 4s2 3d6 4p6 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4

1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 2

How many significant figures does each of these measurements have? 150 ml

2

A calculator answer of 20.0332 must be rounded off to three significant figures. What answer is reported?

20.0

Consider the reaction, 2K3PO4 + 3Ca(NO3)2 → Ca3(PO4)2 + 6KNO3 How many oxygen atoms exist (on either side of the equation)? Remember to add them up carefully. Enter your answer as a number:

26

What is the molar mass of Mg3(PO4)2, a substance formerly used in medicine as an antacid? 71.3 g 263 g 150. g 214 g 118 g

263 g

Which of the following gives a correct and balanced equation for the reaction between sodium phosphate and magnesium chloride to give magnesium phosphate and sodium chloride? Na3PO4(aq) + MgCl2(aq) → Mg3(PO4)2(s) + 3NaCl(aq) 3Na3PO4(aq) + 3MgCl2(aq) → Mg3(PO4)2(s) + 3NaCl(aq) Na3PO4(aq) + MgCl2(aq) → Mg3(PO4)2(s) + NaCl(aq) 2Na3PO4(aq) + 3MgCl2(aq) → Mg3(PO4)2(s) + 6NaCl(aq)

2Na3PO4(aq) + 3MgCl2(aq) → Mg3(PO4)2(s) + 6NaCl(aq)

How many significant figures does each of these measurements have? 10.4 cm

3

What is the coefficient of hydrogen, H2, when the following equation is balanced? Fe(s) + HCl(aq) → FeCl3(aq) + H2(g)

3

Atoms with five valence electrons generally form (#) covalent bond(s) and have (#) lone pair(s) of electrons in molecules.

3 1

How many moles of water, H2O, are present in 55.1 g of H2O?

3.05

What volume would a 0.250 mole sample of H2 gas occupy, if it had a which has a pressure of 1.70 atm, and a temperature of 35 °C? Report the answer to the correct number of significant figures and with the correct units.

3.72 L

What mass in grams of sodium nitride is required to produce 5.43g of nitrogen? Just enter the number. 2Na3N → N2 + 6Na

32.2

A sample of gas contains four gases (He, Ne, Ar, and Xe) with the following partial pressures: He (43 mm Hg), Ar (835 mm Hg), and Xe (111 mm Hg). If the total pressure in the container is 1355 mm Hg, what is the partial pressure of Ne in the sample?

366

What is the percent yield of B in a reaction that uses 12.0 g of starting material A, has a theoretical yield of 17.1 g of B and an actual yield of 6.56 g B? Answer entry format: the % sign is understood here so just enter the number.

38.4

How many significant figures does each of these measurements have? 122,300 km

4

Provide the correct coefficients in the blanks below to balance the reaction. N2 + [#] H2O → N2H4 + [#] H2O2

4 2

Which of the following numbers is the largest? 4.0 × 10-2 4.0 × 10-8 4.0 × 10-12 4.0 × 1015

4.0 × 1015

What are the masses of the following: What does one mole of helium gas weigh to three significant figures? [x] What does one mole of oxygen gas weigh to three significant figures? [y]

4.00 32.0

How many moles of water (H2O) can be produced from 5.8 moles of O2 and an excess amount of C6H14? Write your answer using 2 significant figures. 2 C6H14 (l) + 19 O2 (g) --> 12 CO2 (g) + 14 H2O (g)

4.3

If a package of nuts weighs 1.17 x 106 mg, what is the mass of package reported in ounces? Report your answer, as always, with the correct number of significant figures. Just enter the number value in normal decimal notation and leave out the units. It is understood that it is oz. ( 1 ounce = 28.34952 g)

41.3

A calculator answer of 423.6059 must be rounded off to two significant figures. What answer is reported?

420

A calculator answer of 423.6059 must be rounded off to three significant figures. What answer is reported?

424

How many significant figures does each of these measurements have? 1030.2 L

5

Propane (C3H8) reacts with oxygen to form carbon dioxide and water according to the following (unbalanced) reaction. What is the coefficient for oxygen in the balanced equation? C3H8 + ? O2 → CO2 + H2O Enter number only

5

A gas at 5.00 atm pressure was stored in a tank during the winter at 5.0 °C. During the summer, the temperature in the storage area reached 40.0 °C. What was the pressure in the gas tank then? 40.0 atm 4.44 atm 69.5 atm 5.63 atm 0.625 atm

5.63 atm

How many significant figures does each of these measurements have? 0.500010 g

6

What is the correct answer for the following calculation, reported using the proper number of significant figures: 35.1/5.555

6.32

The number 0.000 000 680 expressed correctly in scientific notation is: 6.8 × 107 68 × 10-7 68 × 107 6.8 × 102

6.80 × 10-7

How many atoms of neon are present in 1.30 moles of neon? 4.63 × 1023 atoms 7.83 × 1023 atom 3.15 × 1023 atoms 6.02 × 1023 atoms

7.83 × 1023 atoms

Consider the transition metal element tungsten, elemental symbol W. The isotope Tungsten-184 has [x] protons, [y] neutrons and [z] electrons.

74 110 74

What is the mass in grams of 87.33 mL of blood plasma with a density of 1.04 g/mL? Here the units are understood to be grams (g), so just enter the numeric answer to the question.

90.8

Which of the following is NOT a characteristic of the atom or the modern periodic table: A period in the periodic table is the same as a group. The electron cloud contains most of the volume of an atom. When orbitals are equal in energy, one electron is added to each orbital until the orbitals are half-filled, before any orbital is completely filled. When two electrons are in the same orbital they must have paired spins—that is, the spins are opposite in direction The farther a shell is from the nucleus, the larger its volume becomes, and the more electrons it can hold

A period in the periodic table is the same as a group.

Enter the chemical formula from the given name here. Note: For these text boxes in which you are entering your answer, subscript and superscript are impossible. Therefore all numbers will be in line with the rest of the text in this case. Silver nitrate Hint Silver has the elemental symbol Ag

AgNO3

What is the correct formula of the ionic compound formed when aluminum and sulfur combine? AlS Al2S3 Al3S2 Al2S AlS3

Al2S3

Which cylinder at STP will contain the greatest number of gas particles? 5.0-L cylinder of neon 5.0-L cylinder of helium 5.0-L cylinder of nitrogen 5.0-L cylinder of hydrogen All of the cylinders above contain the same number of gas particles

All of the cylinders above contain the same number of gas particles

Enter the systematic name for the following substance. Note: format for roman numerals is that you use a capital i and capital v in parentheses where appropriate on your keyboard. NH4Cl

Ammonium chloride

Barium fluoride is used in embalming and in glass manufacturing. Which of the following gives the formula and bonding for barium fluoride? BaF2, ionic compound

BaF2, ionic compound BaF, covalent compound BaF, ionic compound BaF2, covalent compound

What is the symbol and electron configuration of the element in Period 4 and Group 2?

Ca, [Ar]4s2 C, [He]1s2 2s2 Be, [He]2s2 Ca, 1s2 2s2 2p6 3s2 3p6 3d2 C, 1s2 2s2 2p1

Enter the systematic name for the following substance. Note: format for roman numerals is that you use a capital i and capital v in parentheses where appropriate on your keyboard. N2O4

Dinitrogen tetroxide

Rank the atoms K, Br, Cl, and F in order of increasing electronegativity.

K Br Cl F

Select all elements from the list below that are likely to be good conductors of electricity. Fluorine (F) Magnesium (Mg) Argon (Ar) Nickel (Ni) Nitrogen (N) Carbon (C) Oxygen (O) Chlorine (Cl)

Mg Ni

Which chemical formula is correct? AgCl2 K2CN Mg(OH)2 MgNO3 More than one of the above formula are correct.

Mg(OH)2

Enter the chemical formula from the given name here. Note: For these text boxes in which you are entering your answer, subscript and superscript are impossible. Therefore all numbers will be in line with the rest of the text in this case. Magnesium sulfate

MgS4

Enter the chemical formula from the given name here. Note: For these text boxes in which you are entering your answer, subscript and superscript are impossible. Therefore all numbers will be in line with the rest of the text in this case. ammonium sulfite

NH4S2

What is the symbol (1 or 2 letter symbol) of an alkali metal in period 3?

Na

What is the name (spell it out) for a Nobel gas with 10 electrons?

Neon

Enter the chemical formula from the given name here. Note: For these text boxes in which you are entering your answer, subscript and superscript are impossible. Therefore all numbers will be in line with the rest of the text in this case. Tetraphosphorus decoxide

P4O10

Rank the following in terms of increasing atomic radius (i.e. smallest to largest): calcium, silicon, carbon and phosphorus. [a],[b],[c],[d]

Rank the following in terms of increasing atomic radius (i.e. smallest to largest): calcium, silicon, carbon and phosphorus. carbon,phosphorus, silicon, calcium

Enter the chemical formula from the given name here. Note: For these text boxes in which you are entering your answer, subscript and superscript are impossible. Therefore all numbers will be in line with the rest of the text in this case. Hint the symbol for Tin is Sn. Tin(IV) sulfide

SnS2

Nuclear radiation results from: A process that can only be achieved in a laboratory or nuclear power plant. The decay of an unstable nucleus to release energy and a more stable nucleus. The loss of a neutron as a high energy particle. The loss or gain of electrons from the valence shell of an atom.

The decay of an unstable nucleus to release energy and a more stable nucleus.

Consider the reaction: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g), where ΔH = - 531 kcal/mol. Which statement is true? The reaction is exothermic. Heat is absorbed as the reaction proceeds. The reaction is endothermic. The products are higher in energy than the reactants

The reaction is exothermic

The specific heat of copper is 0.0920 cal/g °C, and the specific heat of silver is 0.0562 cal/g °C. If 100 cal of heat is added to one g of each metal at 25 °C, what is the expected result? The copper will reach a higher temperature. The silver will soften. The silver will reach a higher temperature. The two samples will reach the same temperature. The copper will reach a temperature lower than 25 °C.

The silver will reach a higher temperature.

Which has the largest mass? a positron a gamma ray an alpha particle a beta particle

an alpha particle

In a molecule with covalent bonding, atoms of noble gases are held together by attractions between oppositely charged ions. atoms of different metals form bonds. atoms are held together by sharing electrons. atoms of metals form bonds to atoms of nonmetals. oppositely charged ions are held together by strong electrical attractions.

atoms are held together by sharing electrons.

Predict the shape of a molecule of H2S. Hint: first draw the Lewis structure and then use VSEPR theory to determine the shape. The shape will be:

bent

Enter the systematic name for the following substance. Note: format for roman numerals is that you use a capital i and capital v in parentheses where appropriate on your keyboard. CaCO3

calcium carbonate

covalent or ionic? N2O

covalent

The following reaction takes place when an electric current is passed through water. It is an example of a ________ type of reaction. 2H2O → 2H2 + O2

decomposition

Which of the following statements correctly describes valence electrons? electrons located in the nucleus of an atom electrons located in the outermost occupied shell of an atom electrons located in the lowest energy sublevels in an atom electrons located in the innermost shell of an atom, closest to the nucleus

electrons located in the outermost occupied shell of an atom

Which of the following statements correctly describes valence electrons? electrons located in the outermost occupied shell of an atom electrons located in the lowest energy sublevels in an atom electrons located in the innermost shell of an atom, closest to the nucleus electrons located in the nucleus of an atom

electrons located in the outermost occupied shell of an atom

What is the name of the smallest halogen (spell it out) in terms of atomic size?

fluorine

How many electrons does fluorine lose or gain when it forms an ion?

gain 1

covalent or ionic? NaCl

ionic

covalent or ionic? Fe2O3

ionic`

potential energy or kinetic energy burning wood

kinetic energy

potential energy or kinetic energy chewing food

kinetic energy

potential energy or kinetic energy running water

kinetic energy

Which of the following describes an oxidation reaction? Select all that apply. Loss of electrons Gain of oxygen Loss of hydrogen Loss of oxygen Gain of hydrogen Gain of electrons Loss of electrons

loss of electrons gain of oxygen loss of hydrogen loss of electrons

Enter the systematic name for the following substance. Note: format for roman numerals is that you use a capital i and capital v in parentheses where appropriate on your keyboard. MgO

magnesium oxide

Fill in the blanks: In ionic compounds, [a] lose their valence electrons to form positively charged [b], and [c] gain electrons to form negatively charged [d].

metals cations nonmetals anions

In the kinetic molecular theory of gas behavior, the assumption is made that gas molecules decrease kinetic energy as temperature increases. move rapidly in random directions. occasionally come to rest. are close together in their container. are attracted to each other by strong forces

move rapidly in random directions

Which of the following elements will occur as diatomic molecules?. nitrogen hydrogen carbon iodine helium chlorine phosphorus fluorine oxygen bromine selenium sulfur

nitrogen hydrogen iodine chlorine fluorine oxygen bromine

Which one of the following properties describes a liquid? particles are close together and move randomly particles move very rapidly There is essentially no interaction between the particles. has its own shape fills the entire volume of the container

particles are close together and move randomly

potential energy or kinetic energy a coiled spring

potential energy

potential energy or kinetic energy natural gas

potential energy

potential energy or kinetic energy water stored in a reservoir

potential energy

Enter the systematic name for the following substance. Note: format for roman numerals is that you use a capital i and capital v in parentheses where appropriate on your keyboard. SO3

sulfur trioxide

A chemical equation is balanced when the sum of the coefficients of the reactants and the products are equal. the charge on each atom is the same in reactants and products. the number of atoms of each element is the same in reactants and products. the total number of molecules is the same in reactants and products. the total number of ions is the same in reactants and products.

the number of atoms of each element is the same in reactants and products.

According to Avogadro's law the volume of a gas is directly related to the number of moles at constant temperature and pressure. the volume of a gas is inversely related to the number of moles at standard temperature and pressure. the volume of a gas is inversely related to the number of moles at constant temperature and pressure. the volume of a gas the volume of a gas depends only on the temperature and pressure. depends only on the temperature and pressure.

the volume of a gas is directly related to the number of moles at constant temperature and pressure.

What is the term for the heating of a liquid until a gas is formed?

vaporization