Chemistry
Quiz 1, 20013, July 10
Name___________________KEY_______ ID ____________________________
(1)
True or false:
(a)
All neutral atoms contain the same number of
electrons as neutrons
T
F
(b)
1.2300 x 103 has 3 significant figures
T
F
(c)
Chemical properties of elements depend on
valence electrons
T
F
(d)
Scientific theories never change
T
F
T
F
(e)
Photons with twice the wavelength have twice the
energy
(f)
Ions are positively or negatively charged
T
F
(g)
Different elements absorb light at different
wavelengths.
Isotopes have equal numbers of neutrons
T
F
T
F
Ions have equal numbers of protons and
electrons
T
F
(h)
(I)
(2) Smaller – the same – or larger (circle the correct sign):
(3)
(a)
Mass of an electron
<=>
Mass of a proton
(b)
Charge of an proton
Charge of an electron
(c)
Mass of a neutron
(d)
1 mole
<=>
<=>
<=>
Mass of a proton
1 dozen
18 cc of liquid water contains how many molecules?
(a) 1 mole
(b) 6.022 x 1023
(c) Avogadro’s number
(d) all of the above
(e) none of the above
1
(4)
The molar mass of styrene is 104 g/mol. The empirical formula of styrene is CH;
How many moles of H atoms are present in a 208 g sample of styrene?
208 gram is 2 moles of styrene
Mass 104 = 8 x 13 so styrene is C8H8 with 8 H atoms in each styrene
Therefore there are 2 x 8 = 16 moles of H atoms
(5)
1 mole of N2 and 3 moles of H2 react completely with each other to form 2 moles of a
new molecule. What is the formula of that product?
N2 + 3H2  2NH3
(5)
Consider the reaction 2H2 + O2  2H2O.
1 mole of H2 reacts with 1000 moles of O2
How many moles of H2O is formed?
How many grams is that?
H2 is limiting reagent.
1 mole of water is formed
that is 18 grams
(6)
Consider the results from a dart game above. Which are accurate?
(a) 1 and 2
(b) 1 only
(c) 3 and 4
(d) 2 only
2
(e) none of the above
(7)
Light may be described as…
(a) a wave
(b) a beam of photons
(c) a laser
(d) both (a) and (b)
(e) all of the above
(8)
If the world population was 6,775,247,739 people. How could we give this number
with 4 significant figures?
(a) 6775. million
(b) 6.775 x 109
(c) 6.775 billion
(d) all of the above
(9)
X
Y
On the far-way planet Kimchi there are two unusual elements X and Y.
Some of their properties are given below.
Complete the table:
protons
neutrons
electrons
molar mass
7
3
7
10
9
11
9
20
Bonus question:
On that same planet Kimchi those elements form a compound with an empirical formula
XY and a molar mass of 90. What is the molecular formula?
(a) XY
(b) XY3
(c) X3Y
(d) X3Y3
(e) X9Y9
3
4