CHEM 121 EXAM REVIEW SOLVED QUESTIONS COMPLETE ANSWERS GRADED A PLUS

CHEM 121 EXAM REVIEW SOLVED QUESTIONS COMPLETE ANSWERS GRADED A PLUS
CHEM 121 Final EXAM Questions and Answers
Verified Solutions Latest Update 2026/2027

Question:
accuracy refers to

Answer:
how close a measured number is to the true value



Question:
the nucleus of an atom contains

Answer:
protons and neutrons



Question:
the nucleus of an atom DOES NOT contain

Answer:
electrons



Question:
isotopes are atoms that have the same ---- but differing ----

Answer:
atomic numbers; mass numbers the formula of nitrobenzene is C6H5NO2. The molecular weight of
this compound is ---



Question:
amu

,Answer:
123.11



Question:
which one of the following molecular formulas is also an empirical formula?

Answer:
C2H6SO



Question:
a small amount of salt dissolved in water is an example of a ----

Answer:
homogeneous mixture



Question:
the density of a gold nugget is 19.3 g/cm^3. if the volume of the gold nugget is 0.00369 L, the mass
of the nugget is ----

Answer:
71.2



Question:
the element X has three naturally occurring isotopes. the masses (amu) and % abundances of the
isotopes are given in the table below. the average atomic mass of the element is ---- amu

Answer:
220.4



Question:
which species has 54 electrons

, Answer:
^128 52 Te ^2-



Question:
these are all intensive properties

Answer:
density, melting point, boiling point, temperature



Question:
the symbol for the element potassium is

Answer:
K



Question:
of the reactions below, which one is a decomposition reaction

Answer:
NH^4Cl --> NH^3 + HCl



Question:
solid aluminum and gaseous oxygen react in a combination reaction to produce aluminum oxide
4Al(s) + 3O2(g) --> 2Al203 The maximum amount of Al2O3 that can be produced from 2.5 g of Al
and 2.5 g of O2 is ---- g

Answer:
4.7



Question:
the si unit of temperature is ----