Exam Questions and CORRECT Answers
What is chemistry? - CORRECT ANSWER- ✔✔Chemistry is the study of the physical and
compositional changes of matter.
Chemistry is called the Central Science.
Many health related areas of study are based on Chemistry.
Matter - CORRECT ANSWER- ✔✔Matter is anything that has mass, occupies space and is
made-up of atoms or parts of atoms.
Mass - CORRECT ANSWER- ✔✔-Mass is a measure of the amount of matter in an object.
-Mass is independent of the location of an object.
-An object on the earth has the same mass as the same object on the moon, but not same
weight.
Weight - CORRECT ANSWER- ✔✔-Weight is a measure of gravitational force acting on
object.
-Weight depends on the location of an object.
-Force = Mass * Acceleration, F = ma, Wt = m(gravity).
-An object weighing 1.0 lb on earth, weighs about 0.17 lb on the moon. Mass of object is
constant. Moon has 1/6 gravity of earth, which reduces apparent weight of object.
Physical Properties of Matter - CORRECT ANSWER- ✔✔-Physical properties can be
observed or measured without changing the composition of the matter being observed.
Examples of physical properties are: color, shape and mass, and all changes of state like gas
to a liquid.
Chemical Properties of Matter - CORRECT ANSWER- ✔✔-Chemical properties can be
observed or measured only when the composition of matter is changed.
, Examples of chemical properties are flammability and the ability to react (e.g. when vinegar
and baking soda are mixed). Atoms must change partners.
Physical changes of Matter - CORRECT ANSWER- ✔✔-Physical changes are reversible.
-Physical changes take place without a change in composition. Atoms are not changing
partners.
-Nothing new is being created.
Examples of physical changes are freezing, melting, or evaporation of a substance (e.g.
water). H2O(s) → H2O(l), ice → water.
Separation of compounds is a physical change.
ex/ separating iron filing from sand is a chemical reaction
Chemical Changes of matter - CORRECT ANSWER- ✔✔-Chemical changes are not always
reversible.
-Chemical changes are always accompanied by a change in composition. Atoms are changing
partners.
-New types of matter are being created, O2 + 2H2 → 2H2O
Examples of chemical changes are the burning of paper and the fizzing of a mixture of
vinegar and baking soda.
Democritus (Greek, 460-370 BC) - CORRECT ANSWER- ✔✔First person whose writings
suggested,
-based only on logic, that atoms where the
basis of matter.
-Atoms comes from the word 'atomos'
means "no cut".
-Democritus said there were different types of atoms.
-Matter was made of atoms and spaces, call the void.
-Aristotle, (384-322 BC) argued against the possibility of a void and the atomic theory was
lost for nearly 1500 years.