CHEM120/ CHEM 120 EXAM 1: (NEW 2025/ 2026
UPDATE) INTRODUCTION TO GENERAL, ORGANIC &
BIOLOGICAL CHEMISTRY GUIDE| QS & AS| GRADE A|
100% CORRECT (VERIFIED ANSWERS)
Law of Conservation of Mass - ANS ✓Matter is not created nor destroyed in any
chemical or physical change
law of definite proportions - ANS ✓a given compound always contains exactly
the same proportion of elements by mass
Law of Multiple Proportions - ANS ✓if two or more different compounds are
composed of the same two elements, then the ratio of the masses of the second
element combined with a certain mass of the first element is always a ratio of
small whole numbers
Dalton's Atomic Theory - ANS ✓1) elements are composed of atoms. 2) atoms
of same element are identical, but differ from other elements. 3) elements can
mix together 4) atoms only change when mixed with other elements
Proton - ANS ✓positively charged particle
Neutron - ANS ✓no charge
Electron - ANS ✓negatively charged particle
Nucleus - ANS ✓Centre of an atom
atomic number - ANS ✓number of protons
diatomic molecule - ANS ✓A molecule consisting of two atoms
light - ANS ✓a form of electromagnetic radiation that is visible to the eye
Wavelength - ANS ✓(λ) the distance between two peaks
peaks - ANS ✓the top/peak of the wavelength
Chem120/ Chem
, 2
Chem
Frequency - ANS ✓the number of complete wavelengths that pass a point in a
given time
speed - ANS ✓2.9979*10^8 m/s (constant)
Plank's constant - ANS ✓6.626 x 10^-34
long wavelength - ANS ✓low frequency, low energy
short wavelength - ANS ✓high frequency, high energy
photoelectric effect - ANS ✓The emission of electrons from a metal when light
shines on the metal
dimensional analysis - ANS ✓using units as a guide to solving problems
Solid - ANS ✓The particles are tightly packed. The particles do not move around.
liquid - ANS ✓particles are close together with no regular arrangement. Particles
vibrate, move about, and slide past each other.
Gas - ANS ✓Particles are well separated with no regular arrangement. Particles
gas vibrate and move freely at high speeds.
pure substance - ANS ✓composed of only one type of atom or molecule
Mixture - ANS ✓A combination of two or more substances that are not
chemically combined
Element - ANS ✓A pure substance made of only one kind of atom
Compound - ANS ✓A substance made up of atoms of two or more different
elements joined by chemical bonds
chemical change - ANS ✓A change in matter that produces one or more new
substances
homogeneous - ANS ✓same composition throughout
heterogeneous - ANS ✓different composition throughout
Chem120/ Chem
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