AC-HPAT CHEMISTRY QUESTIONS WITH
CORRECT ANSWERS 2025
Double-displacement reaction - CORRECT ANSWER -
A double displacement reaction, also known as a double replacement reaction or metathesis, is a t
ype of chemical reaction where two compounds react, and the positive ions (cation) and the negati
ve 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 insolubl
e solid from solution is called precipitation. Often the precipitate emerges as a suspension. Precipit
ates 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 el
ectrons 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 substanc
e, 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 neutro
ns. 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 p
rocess by which many substances important to daily life are obtained. It is applied to all types of c
hemical 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 i
nto two or more elements or new compounds. These reactions often involve an energy source suc
h 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 an
d takes the place of another element in that compound. This type of reaction is typically pictured l
ike 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 flame
s 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 ion
s in solution.
Organic compounds - CORRECT ANSWER -
An organic compound is a substance that is added to a product, like food, to improve some qualiti
es such as taste, smell, colour 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 mor
e. 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. T
he Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigne
, d L L a L L value L L of L L 4.0, L L and L L values L L range L L down L L to L L caesium L L and L L francium L L which
L L are L L the L L least L L electronegati LLve L L at L L 0.7.
Covalent L L bonds L L - L L CORRECT L L ANSWER L L -Covalent L L bonds L L are L L chemical L L bonds L L between
L L two L L non-
metal L L atoms. L L An L L example L L is L L water, L L where L L hydrogen L L (H) L L and L L oxygen L L (O)
L L bond L L together L L to L L make L L (H2 LLO). L L A L L full L L outer L L shell L L usually L L has L L eight
L L electrons, L L or L L two L L in L L the L L case L L of L L hydrogen L L or L L helium .................................. Cova
lent L L bonds L L are L L formed L L by L L atoms L L sharing L L valence L L electrons.
Functional L L Group L L - L L CORRECT L L ANSWER L L -
The L L functional L L group L L is L L defined L L as L L an L L atom L L or L L group L L of L L atoms L L joined L L in
L L a L L specific L L manner, L L which L L g LLives LLthe LLchemical LLproperties LLof LLthe LLorganic LLcompound
LLand LLare LLthe LLcenters LLfor LLchemical LLreactivity. LLC LLompounds L L having L L a L L similar
L L functional L L group L L have L L undergone L L similar L L reactions.
Unique L L characteristics L L of L L the L L carbon L L atom L L in L L terms L L of L L covalent L L bonding LL-
L L CORRECT L L ANSWER L L -
Because LLeach LLcarbon LLis LLidentical, LLthey LLall LLhave LLfour LLvalence LLelectrons, LLso LLthey LLcan
LLeasily LLbond LLwith L L other L L carbon L L atoms L L to L L form L L long L L chains L L or L L rings. L L In
L L fact, L L a L L carbon L L atom L L can L L bond L L with L L another L L c LLarbon L L atom L L two L L or
L L three L L times L L to L L make L L double L L and L L triple L L covalent L L bonds L L between L L two L L carbon
L L ato LLms.
Alkenes L L - L L CORRECT L L ANSWER L L -
Alkenes LLare LLa LLclass LLof LLhydrocarbons LL(e.g, LLcontaining LLonly LLcarbon LLand LLhydrogen)
LLunsaturated LLcompo LLunds L L with L L at L L least L L one L L carbon-to-
carbon L L double L L bond. L L Another L L term L L used L L to L L describe L L alkenes L L is L L olefins.
L L Alkenes L L are L L more L L reactive L L t LLhan L L alkanes L L due L L to L L the L L presence L L of L L the
L L double L L bond
Alkane L L - L L CORRECT L L ANSWER L L -
an LLalkane, LLor LLparaffin LL(a LLhistorical LLname LLthat LLalso LLhas LLother LLmeanings), LLis LLan LLacyclic
LLsaturated LLhydr LLocarbon. L L In L L other L L words, L L an L L alkane L L consists L L of L L hydrogen L L and
L L carbon L L atoms L L arranged L L in L L a L L tree L L struc LLture L L in L L which L L all L L the L L carbon-
carbon L L bonds L L are L L single.
Alkyne L L - L L CORRECT L L ANSWER L L -
An L L alkyne L L is L L a L L molecule L L that L L has L L a L L triple L L bond L L between L L two L L carbon
L L atoms. L L They L L have L L general L L for LLmula L L cnh2n-
2. L L They L L are L L also L L called L L acetylenes. L L The L L smallest L L alkyne L L is L L acetylene, L L also L L called
L L ethyne. L L Alkynes L L are LLhydrophobic: L L this L L means L L they L L dissolve L L well L L in L L organic
CORRECT ANSWERS 2025
Double-displacement reaction - CORRECT ANSWER -
A double displacement reaction, also known as a double replacement reaction or metathesis, is a t
ype of chemical reaction where two compounds react, and the positive ions (cation) and the negati
ve 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 insolubl
e solid from solution is called precipitation. Often the precipitate emerges as a suspension. Precipit
ates 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 el
ectrons 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 substanc
e, 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 neutro
ns. 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 p
rocess by which many substances important to daily life are obtained. It is applied to all types of c
hemical 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 i
nto two or more elements or new compounds. These reactions often involve an energy source suc
h 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 an
d takes the place of another element in that compound. This type of reaction is typically pictured l
ike 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 flame
s 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 ion
s in solution.
Organic compounds - CORRECT ANSWER -
An organic compound is a substance that is added to a product, like food, to improve some qualiti
es such as taste, smell, colour 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 mor
e. 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. T
he Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigne
, d L L a L L value L L of L L 4.0, L L and L L values L L range L L down L L to L L caesium L L and L L francium L L which
L L are L L the L L least L L electronegati LLve L L at L L 0.7.
Covalent L L bonds L L - L L CORRECT L L ANSWER L L -Covalent L L bonds L L are L L chemical L L bonds L L between
L L two L L non-
metal L L atoms. L L An L L example L L is L L water, L L where L L hydrogen L L (H) L L and L L oxygen L L (O)
L L bond L L together L L to L L make L L (H2 LLO). L L A L L full L L outer L L shell L L usually L L has L L eight
L L electrons, L L or L L two L L in L L the L L case L L of L L hydrogen L L or L L helium .................................. Cova
lent L L bonds L L are L L formed L L by L L atoms L L sharing L L valence L L electrons.
Functional L L Group L L - L L CORRECT L L ANSWER L L -
The L L functional L L group L L is L L defined L L as L L an L L atom L L or L L group L L of L L atoms L L joined L L in
L L a L L specific L L manner, L L which L L g LLives LLthe LLchemical LLproperties LLof LLthe LLorganic LLcompound
LLand LLare LLthe LLcenters LLfor LLchemical LLreactivity. LLC LLompounds L L having L L a L L similar
L L functional L L group L L have L L undergone L L similar L L reactions.
Unique L L characteristics L L of L L the L L carbon L L atom L L in L L terms L L of L L covalent L L bonding LL-
L L CORRECT L L ANSWER L L -
Because LLeach LLcarbon LLis LLidentical, LLthey LLall LLhave LLfour LLvalence LLelectrons, LLso LLthey LLcan
LLeasily LLbond LLwith L L other L L carbon L L atoms L L to L L form L L long L L chains L L or L L rings. L L In
L L fact, L L a L L carbon L L atom L L can L L bond L L with L L another L L c LLarbon L L atom L L two L L or
L L three L L times L L to L L make L L double L L and L L triple L L covalent L L bonds L L between L L two L L carbon
L L ato LLms.
Alkenes L L - L L CORRECT L L ANSWER L L -
Alkenes LLare LLa LLclass LLof LLhydrocarbons LL(e.g, LLcontaining LLonly LLcarbon LLand LLhydrogen)
LLunsaturated LLcompo LLunds L L with L L at L L least L L one L L carbon-to-
carbon L L double L L bond. L L Another L L term L L used L L to L L describe L L alkenes L L is L L olefins.
L L Alkenes L L are L L more L L reactive L L t LLhan L L alkanes L L due L L to L L the L L presence L L of L L the
L L double L L bond
Alkane L L - L L CORRECT L L ANSWER L L -
an LLalkane, LLor LLparaffin LL(a LLhistorical LLname LLthat LLalso LLhas LLother LLmeanings), LLis LLan LLacyclic
LLsaturated LLhydr LLocarbon. L L In L L other L L words, L L an L L alkane L L consists L L of L L hydrogen L L and
L L carbon L L atoms L L arranged L L in L L a L L tree L L struc LLture L L in L L which L L all L L the L L carbon-
carbon L L bonds L L are L L single.
Alkyne L L - L L CORRECT L L ANSWER L L -
An L L alkyne L L is L L a L L molecule L L that L L has L L a L L triple L L bond L L between L L two L L carbon
L L atoms. L L They L L have L L general L L for LLmula L L cnh2n-
2. L L They L L are L L also L L called L L acetylenes. L L The L L smallest L L alkyne L L is L L acetylene, L L also L L called
L L ethyne. L L Alkynes L L are LLhydrophobic: L L this L L means L L they L L dissolve L L well L L in L L organic
