Question

1. name the compound $\ce{n2o4}$.

a. sodium tetroxide
c. nitrous oxide
b. dinitrogen tetroxide
d. binitrogen oxide

1. how many valence electrons does the molecule $\ce{c2h4}$ have?

a. 14
c. 12
b. 10
d. 16

1. name the compound $\ce{cuco3}$.

a. copper (i) carbonate
c. cuprous carbide
b. cupric trioxycarbide
d. copper (ii) carbonate

1. what is the formula for the compound formed by tin (iv) and the chromate ion, $\ce{cro4^{2-}}$?

a. $\ce{sn(cro4)4}$
c. $\ce{sn2(cro4)4}$
b. $\ce{sn2(cro4)2}$
d. $\ce{sn(cro4)2}$

1. the average atomic mass of an element depends on both the mass of its isotopes and each isotope’s...

a. atomic number.
c. percent abundance.
b. radioactivity.
d. mass number.

1. how does the $\ce{se^{2-}}$ ion differ from the se atom? the ion has...

a. fewer electrons.
d. more neutrons.
b. fewer protons.
e. more protons.
c. more electrons.

1. if a chemical were to splash into your eyes, you would need to use the eyewash station to clean out your eyes. in order to avoid this situation, you should...

a. make your lab partner do all the work.
b. wear sunglasses in the lab.
c. do the lab better.
d. put on goggles before doing any lab work.

1. what are the numbers called that are placed in front of an element or compound to balance a chemical equation?

a. subscripts
b. superscripts
c. coefficients
d. none of the above

1. a nuclear particle that has about the same mass as a proton, but with no electrical charge, is called a(n)

a. nuclide
c. electron
b. neutron
d. isotope

1. ionic bonding is...

a. sharing electrons between atoms.
c. turning electrons into protons.
b. transfer of electrons between atoms.
d. between two metals.

Explanation:

1. Q72: For covalent molecular compounds, use prefixes to denote atom counts. $N_2O_4$ has 2 nitrogen and 4 oxygen atoms, so it is dinitrogen tetroxide.
2. Q73: Carbon has 4 valence electrons each, hydrogen has 1 each. $2\times4 + 4\times1 =12$ total valence electrons.
3. Q74: $CO_3^{2-}$ is carbonate ion, copper has +2 charge here to balance it, so it is Copper (II) carbonate.
4. Q75: Tin (IV) is $Sn^{4+}$, chromate is $CrO_4^{2-}$. Cross charges: $Sn^{4+}$ pairs with 2 $CrO_4^{2-}$ to form $Sn(CrO_4)_2$.
5. Q76: Average atomic mass is weighted by the percent natural abundance of each isotope.
6. Q77: $Se^{2-}$ is formed when a neutral Se atom gains 2 electrons, so it has more electrons.
7. Q78: Standard lab safety requires wearing goggles to prevent chemical splashes in eyes.
8. Q79: Leading numbers balancing chemical equations are called coefficients, subscripts are fixed in compound formulas.
9. Q80: Neutrons have nearly identical mass to protons and carry no electrical charge.
10. Q81: Ionic bonds form when electrons transfer from metals to nonmetals creating oppositely charged ions that attract.

Answer:

1. b. Dinitrogen tetroxide
2. c. 12
3. d. Copper (II) carbonate
4. d. $\boldsymbol{Sn(CrO_4)_2}$
5. c. percent abundance.
6. c. more electrons.
7. d. put on goggles before doing any lab work.
8. c. coefficients
9. b. neutron
10. b. transfer of electrons between atoms.