CHEM 120 Homework Chapter  2

1) Which of the following name/discovery/experiment combination is not correct

a)       Rutherford/ nucleus of an atom/a-particle scattering experiment from a gold foil.
b) Thomson/discovery of electron/ Cathode Ray Tubes(CRT).
c) Chadwick/discovery of neutrons/ bombardment of 9Be with a-particles

          (9Be + 4He --> 12C + 1n).
d) Robert Andrew Millikan/protons, positively charged particles/Oil drop experiment.

 

2) Most of the volume of an atom is occupied by the space required for the,
          a) moving electrons       b) protons      c) nucleus      d) neutrons

 

3)  All isotopes of a given element,
    a) possess different masses.                b) possess the same chemical properties.
    c) have the same atomic number)     d) all the above.

4) The 207Pb2+ ion contains
         a) 82 protons, 126 neutrons, and 80 electrons.      b) 82 protons, 125 neutrons, and 80 electrons
         c) 82 protons, 126 neutrons, and 126 electrons.    d) 126 protons, 82 neutrons, and 122 electrons.

5) An atom with 35 protons and 45 neutrons would be an isotope of the element,
          a). rhodium, Rh      b) neon, Ne       c) mercury, Hg      d) bromine, Br

6) How many microliters are in 89.63 L?

a) 8.963 x 10-4 mL    b) 8.963 x 10-7 mL
c) 8.963 x 104 mL    d) 8.963 x 107 mL
e) 8.963 x 1010 mL

7) A box has dimensions of 1.51 in. by 2.74 in. by 4.72 in. What is its volume in cubic centimeters?

a) 1.19 cm3     b) 0.841 cm3
c) 7.69 cm3    d) 320. cm3
e) 49.6 cm3

8) If the isotopic ratio of the two boron isotopes 10B (10.013 amu) and 11B (11.009 amu) has been altered from the ratio found in nature and now contains 48.73% 10B, determine the atomic weight of the sample of boron.

a)       10.811 amu    b) 10.013 amu
c) 11.009 amu   d) 10.524 amu
e) 10.498 amu

19) . In Bohr's theory of the atom, what is the number n (n = 1, 2, 3, 4)

called?

a)      Quantum number   b) Atomic number   c)  Mass number    d)  orbital

 

20)  Explain the meaning/consequences of Heisenberg's

Uncertainty Principle.

a) Electron have wave properties

b)  It is impossible to know the exact position and momentum of a particle,

such as an electron in an atom.

c) Electron absorb energy and get excited to a higher energy level.

d) Certain nuclei decay and change to other types of elements