Chemistry Midterm Review

What is the mass of 0.240 mol glucose, C6H12O6? a. 24.0 g b. 43.2 g c. 180.16 g d. 750. g

b

When a stable covalent bond forms, the potential energy of the atoms a. increases. b. decreases. c. remains constant. d. becomes zero.

b

Which coefficients correctly balance the formula equation NH4NO2(s)→ N2(g) + H2O(l)? a. 1, 2, 2 b. 1, 1, 2 c. 2, 1, 1 d. 2, 2, 2

b

Which model of the atom explains the orbitals of electrons as waves? a. the Bohr model b. the quantum model c. Rutherford's model d. Planck's theory

b

A prospector finds 39.39 g of pure gold (atomic mass 196.9665 a. 1.204 × 1023 atoms of Au. b. 2.308 × 1023 atoms of Au. c. 4.306 × 1023 atoms of Au. d. 6.022 × 1023 atoms of Au.

a

As independent particles, most atoms are a. at relatively high potential energy. b. at relatively low potential energy. c. very stable. d. part of a chemical bond.

a

Because most particles fired at metal foil passed straight through, Rutherford concluded that a. atoms were mostly empty space. b. atoms contained no charged particles. c. electrons formed the nucleus. d. atoms were indivisible.

a

Chlorine has atomic number 17 and mass number 35. It has a. 17 protons, 17 electrons, and 18 neutrons b. 35 protons, 35 electrons, and 17 neutrons. c. 17 protons, 17 electrons, and 52 neutrons. d. 18 protons, 18 electrons, and 17 neutrons.

a

Compared with nonmetals, the number of valence electrons in metals is generally a. smaller. b. greater. c. about the same. d. almost triple.

a

How many molecules are there in 5.0 g of methyl alcohol, CH3OH? a. 9.4 mc066-2.jpg 1022 b. 3.0 mc066-3.jpg 1024 c. 3.6 mc066-4.jpg 1024 d. 3.8 mc066-5.jpg 1024

a

If a mixture is uniform in composition, it is said to be a. homogeneous. b. chemically bonded. c. heterogeneous. d. a compound.

a

If two covalently bonded atoms are identical, the bond is a. nonpolar covalent. b. polar covalent. c. dipole covalent. d. coordinate covalent.

a

In a chemical reaction a. the mass of the reactants equals the mass of the products. b. the mass of the products is greater than the mass of reactants. c. the number of atoms in the reactants and products must change. d. energy as heat must be added to the reactants.

a

The periodic table a. permits the properties of an element to be predicted before the element is discovered. b. will be completed with element 118. c. has been of little use to chemists since the early 1900s. d. was completed with the discovery of the noble gases.

a

Use VSEPR theory to predict the shape of the carbon tetraiodide molecule, CI4. a. tetrahedral b. linear c. bent d. trigonal-planar

a

What is the electron configuration for nitrogen, atomic number 7? a. 1s2 2s2 2p3 b. 1s2 2s3 2p2 c. 1s2 2s3 2p1 d. 1s2 2s2 2p2 3s1

a

What is the formula for the compound formed by lead(II) ions and chromate ions? a. PbCrO4 b. Pb2CrO4 c. Pb2(CrO4)3 d. Pb(CrO4)2

a

A chemical formula includes the symbols of the elements in the compound and subscripts that indicate a. atomic mass of each element. b. number of atoms or ions of each element that are combined in the compound. c. formula mass. d. charges on the elements or ions.

b

A compound is a. a pure substance that cannot be broken down into simpler, stable substances. b. a substance, made of two or more atoms that are chemically bonded, that can be broken down into simpler, stable substances. c. the smallest unit of matter that maintains its chemical identity. d. any substance, whether it is chemically bonded or not.

b

A compound's empirical formula is C2H5. If the formula mass is 58 amu, what is the molecular formula? a. C3H6 b. C4H10 c. C5H8 d. C5H15

b

A line spectrum is produced when an electron moves from one energy level a. to a higher energy level. b. to a lower energy level. c. into the nucleus. d. to another position in the same sublevel.

b

A theory is accepted as the explanation of an observed phenomenon until a. one study contradicts the theory. b. repeated observations conflict with the theory c. a new method is discovered. d. a leading scientist declares that it is invalid.

b

An element in the activity series can replace any element a. in the periodic table. b. below it on the list. c. above it on the list. d. in its group.

b

Dalton's atomic theory agrees with modern atomic theory except for the statement that a. all matter is made up of small particles. b. atoms are not divided in chemical reactions. c. atoms of the same element are chemically alike. d. all atoms of the same element have the same mass.

b

For an electron in an atom to change from the ground state to an excited state, a. energy must be released. b. energy must be absorbed. c. radiation must be emitted. d. the electron must make a transition from a higher to a lower energy level.

b

How many significant figures would the answer to the following calculation have? 3.475 × 1.97 + 2.4712 is a. 2 b. 3 c. 4 d. 5

b

Isotopes are atoms of the same element that have different a. principal chemical properties. b. masses. c. numbers of protons. d. numbers of electrons.

b

Matter includes all of the following except a. air. b. light. c. smoke. d. water vapor.

b

The B—F bond in BF3 (electronegativity for B is 2.0; electronegativity for F is 4.0) is a. polar covalent. b. ionic. c. nonpolar covalent. d. metallic.

b

The average atomic mass of an element a. is the mass of the most abundant isotope. b. may not equal the mass of any of its isotopes c. cannot be calculated. d. always adds up to 100.

b

The deflection of cathode rays in Thomson's experiments was evidence of the ____ nature of electrons. a. wave b. charged c. particle d. spinning

b

The number of significant figures in the measurement 0.000 305 kg is a. 2. b. 3. c. 6. d. 7

b

The two most important properties of all matter are a. the ability to carry an electric current well and to hold electric charge. b. taking up space and having mass. c. being brittle and hard. d. being malleable and ductile.

b

What is the density of 37.72 g of material whose volume is 6.80 cm3? a. 0.180 g/cm3 b. 5.55 g/cm3 c. 30.9 g/cm3 d. 256. g/cm3

b

What is the formula for zinc fluoride? a. ZnF b. ZnF2 c. Zn2F d. Zn2F3

b

A mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together is called a(n) a. dipole. b. Lewis structure. c. chemical bond. d. London force.

c

All of the following are steps in the scientific method except a. observing and recording data. b. forming a hypothesis. c. discarding data inconsistent with the hypothesis d. developing a model based on experimental results.

c

An atom is electrically neutral because a. neutrons balance the protons and electrons. b. nuclear forces stabilize the charges. c. the numbers of protons and electrons are equal. d. the numbers of protons and neutrons are equal.

c

Because a few alpha particles bounced back from the foil, Rutherford concluded that they were a. striking electrons. b. indivisible. c. repelled by densely packed regions of positive charge. d. magnetic.

c

Bohr's theory helped explain why a. electrons have negative charge. b. most of the mass of the atom is in the nucleus. c. excited hydrogen gas gives off certain colors of light. d. atoms combine to form molecules.

c

Compared with ionic compounds, molecular compounds a. have higher boiling points. b. are brittle. c. have lower melting points. d. are harder.

c

How many minutes are in 1 week? a. 168 min b. 1440 min c. 10 080 min d. 100 800 min

c

In a double-displacement reaction, hydrogen chloride and sodium hydroxide react to produce sodium chloride. Another product is a. sodium hydride. b. potassium chloride. c. water. d. hydrogen gas.

c

Name the compound KClO3. a. potassium chloride b. potassium trioxychlorite c. potassium chlorate d. hypochlorite

c

Name the compound SiO2. a. silver oxide b. silicon oxide c. silicon dioxide d. monosilver dioxide

c

Name the compound Zn3(PO4)2. a. zinc potassium oxide b. trizinc polyoxide c. zinc phosphate d. zinc phosphite

c

The density of aluminum is 2.70 g/cm3. What is the mass of a solid piece of aluminum with a volume of 1.50 cm3? a. 0.556 g b. 1.80 g c. 4.05 g d. 4.20 g

c

The empirical formula for a compound shows the symbols of the elements with subscripts indicating the a. actual numbers of atoms in a molecule. b. number of moles of the compound in 100 g. c. smallest whole-number ratio of the atoms. d. atomic masses of each element.

c

The energy of a photon is related to its a. mass. b. speed. c. frequency. d. size.

c

The group of soft, silvery, reactive metals, all of which have one electron in an s orbital, is known as the a. alkaline-earth metals. b. transition metals. c. alkali metals. d. metalloids.

c

The measurement 0.035550 g rounded off to two significant figures would be a. 0.03 g. b. 0.35 g. c. 0.036 g. d. 3.5 × 102 g.

c

The molar mass of NO2 is 46.01 g/mol. How many moles of NO2 are present in 114.95 g? a. 0.4003 mol b. 1.000 mol c. 2.498 mol d. 114.95 mol

c

The molecular formula for vitamin C is C6H8O6. What is the empirical formula? a. CHO b. CH2O c. C3H4O3 d. C2H4O2

c

The reaction represented by the equation Mg(s) + 2HCl(aq) → H2(g) + MgCl2(aq) is a a. composition reaction. b. decomposition reaction. c. single-displacement reaction. d. double-displacement reaction.

c

The substance whose Lewis structure shows three covalent bonds is a. H2O. b. CH2Cl2. c. NH3. d. CCl4.

c

Visible light, X rays, infrared radiation, and radio waves all have the same a. energy. b. wavelength. c. speed. d. frequency.

c

What is the formula for barium hydroxide? a. BaOH b. BaOH2 c. Ba(OH)2 d. Ba(OH)

c

A molecular compound has the empirical formula XY3. Which of the following is a possible molecular formula? a. X2Y3 b. XY4 c. X2Y5 d. X2Y6

d

A physical change occurs when a a. peach spoils. b. silver bowl tarnishes. c. bracelet turns your wrist green. d. glue gun melts a glue stick.

d

All atoms of the same element have the same a. atomic mass. b. number of neutrons. c. mass number. d. atomic number.

d

All of the following are SI units for density except a. kg/m3. b. kg/L. c. g/cm3. d. g/m2.

d

Elements in a group or column in the periodic table can be expected to have similar a. atomic masses. b. atomic numbers. c. numbers of neutrons. d. properties.

d

If repeated measurements agree closely but differ widely from the accepted value, these measurements are a. neither precise nor accurate. b. accurate, but not precise. c. both precise and accurate. d. precise, but not accurate.

d

In the alkaline-earth group, atoms with the smallest radii a. are the most reactive. b. have the largest volume. c. are all gases. d. have the highest ionization energies.

d

In what kind of reaction do two or more substances combine to form a new compound? a. decomposition reaction b. ionic reaction c. double-displacement reaction d. synthesis reaction

d

Question 45 The most characteristic property of the noble gases is that they a. have low boiling points. b. are radioactive. c. are gases at ordinary temperatures. d. are largely unreactive.

d

The Bohr model of the atom was an attempt to explain hydrogen's a. density. b. flammability. c. mass. d. line-emission spectrum.

d

The dimensions of a rectangular solid are measured to be 1.27 cm, 1.3 cm, and 2.5 cm. The volume should be recorded as a. 4.128 cm3. b. 4.12 cm3. c. 4.13 cm3. d. 4.1 cm3.

d

The element with electron configuration 1s2 2s2 2p6 3s2 3p2 is a. Mg (Z = 12). b. C (Z = 6). c. S (Z = 16). d. Si (Z = 14).

d

The equation AX + BY → AY + BX is the general equation for a a. synthesis reaction. b. decomposition reaction. c. single-displacement reaction. d. double-displacement reaction.

d

The mass of a sample containing 3.5 mol of silicon atoms (atomic mass 28.0855 amu) is approximately a. 28 g. b. 35 g. c. 72 g. d. 98 g.

d

The nucleus of an atom has all of the following characteristics except that it a. is positively charged. b. is very dense. c. contains nearly all of the atom's mass. d. contains nearly all of the atom's volume.

d

The region outside the nucleus where an electron can most probably be found is the a. electron configuration. b. quantum. c. s sublevel. d. electron cloud.

d

What is the formula for dinitrogen trioxide? a. Ni2O3 b. NO3 c. N2O6 d. N2O3

d

What is the percentage composition of CO? a. 50% C, 50% O b. 12% C, 88% O c. 25% C, 75% O d. 43% C, 57% O

d

Which equation is not balanced? a. 2H2 + O2→ 2H2O b. 4H2 + 2O2→ 4H2O c. H2 + H2 + O2→ H2O + H2O d. 2H2 + O2→ H2O

d

Which observation does not indicate that a chemical reaction has occurred? a. formation of a precipitate b. production of a gas c. evolution of heat and light d. change in total mass of substances

d

Which of the following is not a physical change? a. grinding b. cutting c. boiling d. burning

d

Which of the following observations is qualitative? a. A chemical reaction was complete in 2.3 seconds. b. The solid had a mass of 23.4 grams. c. The pH of a liquid was 5. d. Salt crystals formed as the liquid evaporated.

d