CHEMISTRY SEMESTER B COMPREHENSIVE
EXAMINATION 2026 COMPLETE QUESTIONS
CORRECT ANSWERS
◉ law of conservation of matter. Answer: Matter is not created nor
destroyed in any chemical or physical change
◉ balancing equations. Answer: coefficients are placed in front of
compounds to observe the law of conservation of mass; must be
equal on both sides
◉ balancing equation ex.. Answer: nitrogen (N2) and oxygen (O2);
unbalanced equation: N2+O2 -> N2 O5; add correct coefficients to
balance equation; (N2+5O2 -> 2N2O5) <- still not balanced;
balanced equation = 2N2+5O2 -> 2N2 O5
◉ (aq). Answer: abbr. for substances dissolved in water
◉ balancing chemical equations with substitution. Answer: Fe2 O3 +
H2 (SO4) -> Fe2 (SO4)3 + H2O; *x=SO4; Fe2/2 O3/3 + 3H2/6 *x/3 ->
Fe2/2 *x3/3 + 3H2/6 O/3
,◉ balanced chemical equation. Answer: represents the relative
amounts of substances required for a complete chemical reaction to
occur
◉ mole. Answer: the SI base unit used to measure the amount of a
substance
◉ formula mass for covalent substances. Answer: formula
represents the numbers and types of atoms composing a single
molecule of the substance; formula mass= molecular mass
◉ ex. chloroform (CHCl3). Answer: (covalent compound) formula
indicates that a single molecule contains one carbon atom, one
hydrogen atom, and three chlorine atoms; avg molecular mass of
chloroform= to sum of the avg. atomic masses of these atoms
◉ calculation used to derive molecular mass of chloroform. Answer:
119.37 amu
◉ formula mass for ionic compounds. Answer: quantity x avg.
atomic mass (amu) = subtotal (each separate element) and then add
all together to get molecular mass
◉ # of particles composing of a mole (named Avogadro's # or
constant). Answer: 6.022 x 10^23
, ◉ molecular mass. Answer: The sum of the masses of all the atoms
in a molecule; sometimes called molecular weight; in grams of one
mole of that substance (grams per mole= g/mol)
◉ mass and chemical composition of a substance. Answer: = # of
moles and calculate # of atoms or molecules in sample
◉ # of moles of substance. Answer: derive # of atoms or molecules
and calculate substances mass
◉ one mole. Answer: = molecular mass of element/ compound
◉ percent composition. Answer: the elemental makeup of a
compound defines its chemical identity, and chemical formulas are
the most succinct way of representing this elemental makeup
◉ when a compound's formula is unknown. Answer: = measuring
mass of each of its elements is often the first step in the process of
determining the formula
◉ % composition - definition. Answer: defined as the percent by
mass of each element in the compound; to calculate you must know
the mass of element or compound
EXAMINATION 2026 COMPLETE QUESTIONS
CORRECT ANSWERS
◉ law of conservation of matter. Answer: Matter is not created nor
destroyed in any chemical or physical change
◉ balancing equations. Answer: coefficients are placed in front of
compounds to observe the law of conservation of mass; must be
equal on both sides
◉ balancing equation ex.. Answer: nitrogen (N2) and oxygen (O2);
unbalanced equation: N2+O2 -> N2 O5; add correct coefficients to
balance equation; (N2+5O2 -> 2N2O5) <- still not balanced;
balanced equation = 2N2+5O2 -> 2N2 O5
◉ (aq). Answer: abbr. for substances dissolved in water
◉ balancing chemical equations with substitution. Answer: Fe2 O3 +
H2 (SO4) -> Fe2 (SO4)3 + H2O; *x=SO4; Fe2/2 O3/3 + 3H2/6 *x/3 ->
Fe2/2 *x3/3 + 3H2/6 O/3
,◉ balanced chemical equation. Answer: represents the relative
amounts of substances required for a complete chemical reaction to
occur
◉ mole. Answer: the SI base unit used to measure the amount of a
substance
◉ formula mass for covalent substances. Answer: formula
represents the numbers and types of atoms composing a single
molecule of the substance; formula mass= molecular mass
◉ ex. chloroform (CHCl3). Answer: (covalent compound) formula
indicates that a single molecule contains one carbon atom, one
hydrogen atom, and three chlorine atoms; avg molecular mass of
chloroform= to sum of the avg. atomic masses of these atoms
◉ calculation used to derive molecular mass of chloroform. Answer:
119.37 amu
◉ formula mass for ionic compounds. Answer: quantity x avg.
atomic mass (amu) = subtotal (each separate element) and then add
all together to get molecular mass
◉ # of particles composing of a mole (named Avogadro's # or
constant). Answer: 6.022 x 10^23
, ◉ molecular mass. Answer: The sum of the masses of all the atoms
in a molecule; sometimes called molecular weight; in grams of one
mole of that substance (grams per mole= g/mol)
◉ mass and chemical composition of a substance. Answer: = # of
moles and calculate # of atoms or molecules in sample
◉ # of moles of substance. Answer: derive # of atoms or molecules
and calculate substances mass
◉ one mole. Answer: = molecular mass of element/ compound
◉ percent composition. Answer: the elemental makeup of a
compound defines its chemical identity, and chemical formulas are
the most succinct way of representing this elemental makeup
◉ when a compound's formula is unknown. Answer: = measuring
mass of each of its elements is often the first step in the process of
determining the formula
◉ % composition - definition. Answer: defined as the percent by
mass of each element in the compound; to calculate you must know
the mass of element or compound
