AC-HPAT Chemistry questions and answers
2025-2026
Double-displacement reaction - CORRECT ANSWER-A double displacement reaction,
also known as a double replacement reaction or metathesis, is a type of chemical
reaction where two compounds react, and the positive ions (cation) and the negative
ions (anion) of the two reactants switch places, forming two new compounds or
products
Precipitate - CORRECT ANSWER-precipitate is an insoluble solid that emerges from a
liquid solution. The emergence of the insoluble solid from solution is called precipitation.
Often the precipitate emerges as a suspension. Precipitates can form when two soluble
salts react in solution to form one or more insoluble products.
Energy Levels - CORRECT ANSWER-Energy levels (also called electron shells) are
fixed distances from the nucleus of an atom where electrons may be found. As you go
farther from the nucleus, electrons at higher energy levels have more energy. Electrons
in the outermost energy level of an atom are called valence electrons
Marquis Test - CORRECT ANSWER-The Marquis Test is commonly used for Ecstasy
testing as MDMA turns the precipitate purple black. Cobalt thiocyanate is used to test
for cocaine. The Cobalt is mixed with the questionable substance, then drowned in
hydrochloric acid, doused in chloroform, and shaken.
What is the relation between an atomic number and a mass number? - CORRECT
ANSWER-Atomic number is actually the number of protons in an atom while mass
number is the number of nucleons I. e, number of protons plus the number of neutrons.
Isotopes - CORRECT ANSWER-Isotopes refer to the nuclides of a certain element that
have different numbers of neutrons, or in other words, atomic nuclei that have the same
number of protons but different numbers of neutrons. A radioisotope is an isotope that is
unstable and therefore undergoes radioactive decay or will at some point.
Chemical Synthesis - CORRECT ANSWER-Chemical synthesis, the construction of
complex chemical compounds from simpler ones. It is the process by which many
substances important to daily life are obtained. It is applied to all types of chemical
compounds, but most syntheses are of organic molecules.
, Decomposition - CORRECT ANSWER-A decomposition reaction is a type of chemical
reaction in which a single compound breaks down into two or more elements or new
compounds. These reactions often involve an energy source such as heat, light, or
electricity that breaks apart the bonds of compounds
single-displacement reaction - CORRECT ANSWER-A single-displacement reaction,
also known as a single-replacement reaction, is a type of chemical reaction where an
element reacts with a compound and takes the place of another element in that
compound. This type of reaction is typically pictured like this: Here, a replaces B in the
compound BC
Flame test - CORRECT ANSWER-flame test is an analytical procedure used in
chemistry to detect the presence of certain elements, primarily metal ions, based on
each element's characteristic emission spectrum. The color of flames in general also
depends on temperature; see flame color.
Precipitation reaction - CORRECT ANSWER-A precipitation reaction refers to the
formation of an insoluble salt when two solutions containing soluble salts are combined.
The insoluble salt that falls out of solution is known as the precipitate, hence the
reaction's name. Precipitation reactions can help determine the presence of various ions
in solution.
organic compounds - CORRECT ANSWER-An organic compound is a substance that is
added to a product, like food, to improve some qualities such as taste, smell, color and
texture. These substances can be both positive and negative for human health.
Synthetic materials - CORRECT ANSWER-Synthetic materials which are by-products of
petroleum are non-biodegradable, synthetic products take a long time to decompose,
creating long-term pollution. Nylon is hard to recycle, making them hard to decompose,
accumulate landfills more. Polyesters are easy to recycle, which makes them less
harmful to the society.
Electronegativity - CORRECT ANSWER-Electronegativity is a measure of the tendency
of an atom to attract a bonding pair of electrons. The Pauling scale is the most
commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0,
and values range down to cesium and francium which are the least electronegative at
0.7.
Covalent bonds - CORRECT ANSWER-Covalent bonds are chemical bonds between
two non-metal atoms. An example is water, where hydrogen (H) and oxygen (O) bond
2025-2026
Double-displacement reaction - CORRECT ANSWER-A double displacement reaction,
also known as a double replacement reaction or metathesis, is a type of chemical
reaction where two compounds react, and the positive ions (cation) and the negative
ions (anion) of the two reactants switch places, forming two new compounds or
products
Precipitate - CORRECT ANSWER-precipitate is an insoluble solid that emerges from a
liquid solution. The emergence of the insoluble solid from solution is called precipitation.
Often the precipitate emerges as a suspension. Precipitates can form when two soluble
salts react in solution to form one or more insoluble products.
Energy Levels - CORRECT ANSWER-Energy levels (also called electron shells) are
fixed distances from the nucleus of an atom where electrons may be found. As you go
farther from the nucleus, electrons at higher energy levels have more energy. Electrons
in the outermost energy level of an atom are called valence electrons
Marquis Test - CORRECT ANSWER-The Marquis Test is commonly used for Ecstasy
testing as MDMA turns the precipitate purple black. Cobalt thiocyanate is used to test
for cocaine. The Cobalt is mixed with the questionable substance, then drowned in
hydrochloric acid, doused in chloroform, and shaken.
What is the relation between an atomic number and a mass number? - CORRECT
ANSWER-Atomic number is actually the number of protons in an atom while mass
number is the number of nucleons I. e, number of protons plus the number of neutrons.
Isotopes - CORRECT ANSWER-Isotopes refer to the nuclides of a certain element that
have different numbers of neutrons, or in other words, atomic nuclei that have the same
number of protons but different numbers of neutrons. A radioisotope is an isotope that is
unstable and therefore undergoes radioactive decay or will at some point.
Chemical Synthesis - CORRECT ANSWER-Chemical synthesis, the construction of
complex chemical compounds from simpler ones. It is the process by which many
substances important to daily life are obtained. It is applied to all types of chemical
compounds, but most syntheses are of organic molecules.
, Decomposition - CORRECT ANSWER-A decomposition reaction is a type of chemical
reaction in which a single compound breaks down into two or more elements or new
compounds. These reactions often involve an energy source such as heat, light, or
electricity that breaks apart the bonds of compounds
single-displacement reaction - CORRECT ANSWER-A single-displacement reaction,
also known as a single-replacement reaction, is a type of chemical reaction where an
element reacts with a compound and takes the place of another element in that
compound. This type of reaction is typically pictured like this: Here, a replaces B in the
compound BC
Flame test - CORRECT ANSWER-flame test is an analytical procedure used in
chemistry to detect the presence of certain elements, primarily metal ions, based on
each element's characteristic emission spectrum. The color of flames in general also
depends on temperature; see flame color.
Precipitation reaction - CORRECT ANSWER-A precipitation reaction refers to the
formation of an insoluble salt when two solutions containing soluble salts are combined.
The insoluble salt that falls out of solution is known as the precipitate, hence the
reaction's name. Precipitation reactions can help determine the presence of various ions
in solution.
organic compounds - CORRECT ANSWER-An organic compound is a substance that is
added to a product, like food, to improve some qualities such as taste, smell, color and
texture. These substances can be both positive and negative for human health.
Synthetic materials - CORRECT ANSWER-Synthetic materials which are by-products of
petroleum are non-biodegradable, synthetic products take a long time to decompose,
creating long-term pollution. Nylon is hard to recycle, making them hard to decompose,
accumulate landfills more. Polyesters are easy to recycle, which makes them less
harmful to the society.
Electronegativity - CORRECT ANSWER-Electronegativity is a measure of the tendency
of an atom to attract a bonding pair of electrons. The Pauling scale is the most
commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0,
and values range down to cesium and francium which are the least electronegative at
0.7.
Covalent bonds - CORRECT ANSWER-Covalent bonds are chemical bonds between
two non-metal atoms. An example is water, where hydrogen (H) and oxygen (O) bond
