Chemistry Test

1. Subatomic particles with a negative charge

• Electrons

• protons

• neutrons

The noble gases, such as helium "He" and xenon "Xe", are non-reactive because:

• they are chemically unstable

• they have been around longest on the Earth

• They have completely filled their outer electron shells

• they are unusually large atoms.

Elements in the same column on the periodic table have similar chemical re-activity because:

• They contain similar amounts of energy levels

• they have the same number of valence shell electrons

• atoms prefer to have completely full or completely empty valence shells

• they have similar numbers of isotopes

How many neutrons does the isotope below have? ⁸⁹ ₃₆Kr

• 53

• 39

• 123

• 36

If X is the symbol for an element, which of the following two symbols represent isotopes of the same element?

I. ⁷⁷₃₅X

II. ⁷⁷₃₃X

III. ⁸¹₃₇X

IV. ⁸¹₃₅ X

• I and II

• III and IV

• I and III

• I and IV

Which is NOT an example of a physical change?

• tearing paper

• chopping wood

• molding clay

• burning wood

What is an atom that has an unstable nucleus and undergoes radioactive decay?

• Radiation

• Radioisotopes

• Radioactivity

The following are pure substances EXCEPT:

• oxygen

• water

• lemonade

• sand

Which of the following statements are true for pure substances?

• pure substances contain only one kind of particles

• pure substances have the same composition throughout

• pure substances may be compound or mixtures

• Pure substance can be exemplified by all elements other than nickel

Name the techniques depicted in the picture.

• Colloidal

• Tyndall

• Suspension

• Brownian