Exam 3

A 10 ohm resistor has 5 A current in it. What is the voltage across the resistor (Hint: Ohm's law)? more than 20 Volts 15 volts 5 volts 10 volts 20 volts

more than 20 Volts

Which set of coefficients balance the following chemical equation? _____MgO + _____Fe -----> ______Fe2O3 + _______Mg A) 3, 2, 1, 3 B) 1, 2, 3, 3 C) 3, 4, 1, 3 D) 1, 2, 1, 3

A) 3, 2, 1, 3

Which set of coefficients balance the following chemical equation? _________Al + ____________O2 --------------> Al2O3 A) 4, 3, 2 B) 2, 3, 2 C) 2, 3, 1 D) 4, 6, 2

A) 4, 3, 2

Which has the greatest number of protons in its nucleus (Hint: use the periodic table)? A) Lead B) Gold C) Mercury D) Silver

A) Lead

Which of the following statements is true? A) There are only about 108 different kinds of atoms that combine to form all substances B) There are thousands of different kinds of atoms that account for a wide variety of substances. C) An atom is the smallest particle known to exist. D) None of the other statements are true.

A) There are only about 108 different kinds of atoms that combine to form all substances

Atoms of metallic elements can form ionic bonds, but they are not very good at forming covalent bonds. Why? A) They have a great tendency to lose electrons. B) Their valence shells are already filled with electrons. C) These atoms are too large to be able to come in close contact with other atoms. D) They are on the wrong side of the periodic table.

A) They have a great tendency to lose electrons.

In the boxes below, solid circles represent the atoms of one element, while the hollow circles represent the atoms of a second element. A physical change is best represented by the transformation of box X into box ________. A) a B) c C) d D) b

A) a - the box with the same number of solid circles but spread out

As more lamps are put into a series circuit, the overall current in the power source A) decreases B) increases C) stays the same

A) decreases

If aluminum ions have a 3+ charge and a sulfur ions have a 2- charge, the compound aluminum sulfide is (Hint: the molecule is neutral) Al2S3 Al2S2 Al3S2 Al3S3

Al2S3

Which set of coefficients balance the following chemical equation? ______NaClO3 ---------> ____________NaCl + ___________O2 A) 1, 1, 2 B) 2, 2, 3 C) 1, 1, 1 D) 2, 2, 5

B) 2, 2, 3

How is a physical change different from a chemical change? A) A physical change involves changes in chemical properties B) The chemical identity of a substance is not altered during a physical change. C) The chemical identity of a substance is altered during a physical change. D) The physical properties of a substance are not altered during a chemical change.

B) The chemical identity of a substance is not altered during a physical change.

The electrical forces between charges depends on the (Hint: Coulomb's law) A) magnitude of electric charges. B) all of the other answers C) separation distance between electric charges.

B) all of the other answers

Two lamps, one with a thick filament and one with a thin filament, are connected in parallel to a battery. The voltage is greatest across the lamp with the A) thick filament B) both voltages are the same C) thin filament

B) both voltages are the same

Charge carriers in a metal are electrons rather than protons because electrons are A) smaller B) loosely bound C) all of the other answers D) negative

B) loosely bound

Connect a pair of lamps in series and you draw current from the connecting battery. Connect the same lamps in parallel and you draw A) less current. B) more current. C) the same current. D) sometimes more, sometimes less.

B) more current.

A positive ion has more A) protons than neutrons. B) protons than electrons C) neutrons than protons D) electrons than neutrons E) electrons than protons.

B) protons than electrons

In an electric circuit, the safety fuse is connected to the circuit in A) parallel B) series

B) series

What makes an element distinct? A) the total mass of all the particles B) the number of protons C) the number of neutrons D) the number of electrons

B) the number of protons

Two charged particles held close to each other are released. As they move, the force on each particle increases. Therefore, the particles have (Hint: Coulomb's law) A) not enough information given B) the opposite sign. C) the same sign.

B) the opposite sign.

How many shells are occupied by electrons in the gold atom (Au, atomic #79)? A) 4 B) 7 C) 6 D) 5

C) 6

What is the difference between an element and a chemical compound? A) Only elements are normally found in nature. B) Only chemical compounds are normally found in nature. C) An element consist of only one type of atom D) A chemical compound is always more massive than an element

C) An element consist of only one type of atom

Which molecule is most polar? (Hint: one end of the molecule has a positive electrical charge and the other side has a negative charge.) A) they all have the same polarity B) s=C=S C) O=C=S D) O=C=O

C) O=C=S

In the boxes below, solid circles represent the atoms of one element, while the hollow circles represent the atoms of a second element. Of the four boxes shown, which contain elements? A) b and c B) a, c and d C) all of the boxes D) a and c E) b and d

C) all of the boxes - trick question!

In an electrically neutral atom the number of protons in the nucleus is equal to the number of A) none of the other answers B) neutrons in the nucleus. C) electrons that surround the nucleus

C) electrons that surround the nucleus

Helium, He, is a nonmetallic gas and the second element in the periodic table. Rather than being placed adjacent to hydrogen, H, however, helium is placed on the far right of the table because A) they come from different sources. B) the sizes of their atoms are vastly different. C) helium is most similar to other group 18 elements. D) hydrogen and helium repel one another.

C) helium is most similar to other group 18 elements.

The atoms of materials that conduct electricity best tend to be held together by A) ionic bonds. B) covalent bonds. C) metallic bonds D) polar covalent bonds

C) metallic bonds

The atoms of a polar covalent bond A) Two of the above are correct B) must include a metal and a nonmetal. C) must be of different elements D) are always of the same element.

C) must be of different elements

How many electrons are shared in a single covalent bond? A) 4 B) 1 C) 6 D) 2

D) 2

How can a hydrogen atom, which has only one electron, have so many spectral lines? (Hint: think about energy levels) A) The atomic radius of the hydrogen atom is relatively large. B) The protons in the nucleus are also giving off various light frequencies C) Because the electron is able to move at various speeds. D) One electron can be boosted to many different energy levels.

D) One electron can be boosted to many different energy levels.

If two protons are removed from an oxygen nucleus, the result is (Hint: use the periodic table) A) helium B) neon C) nitrogen D) carbon

D) carbon

Each solid circle in the above boxes represents an atom of the same element. Each hollow circle represents an atom of a second element. The transformation from left to right is best viewed as a A) chemical change because two types of atoms are involved. B) physical change because there are the same number of atoms in both boxes. C) chemical change because there are a different number of molecules in each box. D) chemical change because the atoms are connected differently in each box.

D) chemical change because the atoms are connected differently in each box. - 1st box paired one of each, 2nd box triplets

Each circle in the above boxes represents an atom of the same element. The transformation from left to right is best viewed as a A) physical change because there are the same number of atoms in both boxes. B) chemical change because there are a different number of molecules in each box. C) physical change because only one type of atom is involved. D) chemical change because the atoms are connected differently in each box.

D) chemical change because the atoms are connected differently in each box. - 6 atoms in the first box in pairs, 6 atoms in the second box in triplets

What elements tend to form ionic compounds? A) metallic elements B) those found in the upper right hand side of the periodic table C) Any two elements of the same phase can form an ionic compound. D) elements found on opposite sides of the periodic table

D) elements found on opposite sides of the periodic table

Covalent and ionic bonds differ in that A) covalent bonds much less common. B) ionic bonds are electrical by nature. C) covalent bonds are more permanent. D) ionic bonds don't involve the sharing of electrons.

D) ionic bonds don't involve the sharing of electrons.

The neon atom tends NOT to gain any additional electrons because A) its nuclear charge is not great enough. B) of the repulsions they would experience with electrons in the same shell. C) that would result in a positive ion. D) there is no more room available in its outermost occupied shell.

D) there is no more room available in its outermost occupied shell.

Two charges separated by one meter exert a 1-N force on each other. If the charges are pushed to 0.25-m separation, the force on each charge will be (Hint: Coulomb's law) A) 8 N B) 4 N C) 2 N D) 1 N E) 16 N

E) 16 N

In the boxes below, solid circles represent the atoms of one element, while the hollow circles represent the atoms of a second element. Of the four boxes shown, which contain(s) chemical compounds? A) b, c, and d B) d only C) b and c D) all of the boxes E) b and d

E) b and d - Box B solid & hollow paired one of each, Box D some solid & hollow paired one of each

A chemical change is best represented by the transformation of box X into box ________. A) d B) a C) c D) b E) none of the other answers

E) none of the other answers - left box all solid at the bottom - 1st box all solid spread out, 2nd box solid & empty paired, 3rd box all solid at the top, 4th box all solid and larger