PSB-HO Natural Science Chemistry (III)
Exam Questions and Answers 2025
Matter- j- jANS✓✓-Substances jthat jhas jmass jand joccupies jspace j(volume).
Mass- j- jANS✓✓-is ja jmeasure jof jthe jamount jof jsubstance jin jan jobject.
Weight- j- jANS✓✓-is ja jmeasure jof jthe jgravitational jpull jof jearth jon jany jobject.
The j4 jstates jof jmatter j& jtheir jcharacteristics: j- jANS✓✓-1. jSolid- jdense jand
jrigid jwith jstrong jbonds.
2. jLiquid- jnot jdense jand jmove jaround jeasily jand jhave jweak jbonds.
3. jGas- jatoms jmove jaround jindependently jand jdo jnot jform jbonds.
4. jPlasma- jionized jgas jthat jhas jsome jelectrons jthat jare jfree jbecause jthey jare
jnot jbound jto jan jatom jor jmolecule.
Volume- j- jANS✓✓-is jthe jmeasure jof jthe jamount jof jspace joccupied.
Density- j- jANS✓✓-is ja jmeasure jof jthe jamount jof jmass jper junit jvolume. j
j- jD j= jm/V
Specific jgravity- j- jANS✓✓-is ja jmeasure jof jthe jratio jof ja jsubstance's jdensity
jcompared jto jthe jdensity jof jwater.
What jcauses jthe jdifferent jstates jof jmatter? j- jANS✓✓-The jdifferences jin
jdistance jand jangles jbetween jmolecules jor jatoms.
All jmatter jconsists jof j______________ jwhich jconsist j____________ j&
j________________. j- jANS✓✓-Atoms, jwhich jconsist jof ja jnucleus jand jelectrons.
The jnucleus jof ja jatoms: j- jANS✓✓-- jhas jprotons jand jneutrons
- jis jpositively jcharged
-is jmore jdense jand jheavier jthan jthe jsurrounding jelectrons
An jion- j- jANS✓✓-is ja jatom jwith ja jnegative jor jpositive jcharge.
An jelement- j- jANS✓✓-is jmatter jwith jone jparticular jtype jof jatom.
, Atomic jnumber- j- jANS✓✓-is jthe jnumber jof jprotons jin jthe jnucleus jof jan jatom.
j- jis jrepresented jas jZ
Atomic jmass- j- jANS✓✓-the jnumber jof jprotons jand jneutrons jfound jin jan jatom
j- jis jreffered jto jas jA
A j(atomic jmass) j= jZ j(# jof jprotons) j+ jN j(# jof jneutrons)
j** jthe jmass jof jelectrons jis jbasically jso jinsignificant jbecause jit jis jso jsmall.
Atomic jWeight- j- jANS✓✓-AKA jrelative jatomic jmass
Is jthe jratio jof jthe javerage jmass jper jatom jof ja jsample. j
Carbon-12: j0.9889 jx j12.0000 j= j11.8668
Carbon-13: j0.0111 jx j13.0034 j= j0.1443
11.8668 j+ j0.1443 j= j12.0111 j= jatomic jweight jof jcarbon
How jmany jelements jare jthere? jAnd jhow jmany jare jare jnaturally joccuring? j-
jANS✓✓-117 jelements, j94 jof jwhich joccur jnaturally jon jEarth.
Compounds- j- jANS✓✓-Substances jcontaining jtwo jor jmore jelements. j
- jare jdecomposed jby jchemically jreactions jrather jthan jseparated jby jphysical
jones.
Solutions- j- jANS✓✓--Are jhomogeneous jmixtures. j
-Uniform jin jtheir jcomposition. j
-Consist jof ja jsolute j(the jsubstance jthat jis jdissolved) jand ja jsolvent j(the
jsubstance jthat jdoes jthe jdissolving)
Mixtures- j- jANS✓✓-contain jtwo jor jmore jdifferent jsubstances jthat jare
jphysically jmixed jbut jnot jchemically jcombined.
j-can jbe jseparated jby jphysical jmethods j(while jcompounds jcan jnot).
Solvation- j- jANS✓✓-The jintermolecular jattraction jbetween jthe jsolvent jand jthe
jsolute.
Hydration- j- jANS✓✓-refers jto jsolutions jin jwhich jwater jis jthe jsolvent.
In jmolecular jformulas, jmolecules jare jorganized jaccording jto jthe j__________
jsystem. j- jANS✓✓-Hill jsystem. j
- jCarbon jfirst, jthen jhydrogen, jthen jthe jremaining jelements jin jalphabetical
jorder. j
- jIf jthere jare jno jcarbon jatoms jthan jall jare jorganized jalphabetically. j
*exceptions: j
j-Oxygen jis jusually jlisted jlast jin joxides
Exam Questions and Answers 2025
Matter- j- jANS✓✓-Substances jthat jhas jmass jand joccupies jspace j(volume).
Mass- j- jANS✓✓-is ja jmeasure jof jthe jamount jof jsubstance jin jan jobject.
Weight- j- jANS✓✓-is ja jmeasure jof jthe jgravitational jpull jof jearth jon jany jobject.
The j4 jstates jof jmatter j& jtheir jcharacteristics: j- jANS✓✓-1. jSolid- jdense jand
jrigid jwith jstrong jbonds.
2. jLiquid- jnot jdense jand jmove jaround jeasily jand jhave jweak jbonds.
3. jGas- jatoms jmove jaround jindependently jand jdo jnot jform jbonds.
4. jPlasma- jionized jgas jthat jhas jsome jelectrons jthat jare jfree jbecause jthey jare
jnot jbound jto jan jatom jor jmolecule.
Volume- j- jANS✓✓-is jthe jmeasure jof jthe jamount jof jspace joccupied.
Density- j- jANS✓✓-is ja jmeasure jof jthe jamount jof jmass jper junit jvolume. j
j- jD j= jm/V
Specific jgravity- j- jANS✓✓-is ja jmeasure jof jthe jratio jof ja jsubstance's jdensity
jcompared jto jthe jdensity jof jwater.
What jcauses jthe jdifferent jstates jof jmatter? j- jANS✓✓-The jdifferences jin
jdistance jand jangles jbetween jmolecules jor jatoms.
All jmatter jconsists jof j______________ jwhich jconsist j____________ j&
j________________. j- jANS✓✓-Atoms, jwhich jconsist jof ja jnucleus jand jelectrons.
The jnucleus jof ja jatoms: j- jANS✓✓-- jhas jprotons jand jneutrons
- jis jpositively jcharged
-is jmore jdense jand jheavier jthan jthe jsurrounding jelectrons
An jion- j- jANS✓✓-is ja jatom jwith ja jnegative jor jpositive jcharge.
An jelement- j- jANS✓✓-is jmatter jwith jone jparticular jtype jof jatom.
, Atomic jnumber- j- jANS✓✓-is jthe jnumber jof jprotons jin jthe jnucleus jof jan jatom.
j- jis jrepresented jas jZ
Atomic jmass- j- jANS✓✓-the jnumber jof jprotons jand jneutrons jfound jin jan jatom
j- jis jreffered jto jas jA
A j(atomic jmass) j= jZ j(# jof jprotons) j+ jN j(# jof jneutrons)
j** jthe jmass jof jelectrons jis jbasically jso jinsignificant jbecause jit jis jso jsmall.
Atomic jWeight- j- jANS✓✓-AKA jrelative jatomic jmass
Is jthe jratio jof jthe javerage jmass jper jatom jof ja jsample. j
Carbon-12: j0.9889 jx j12.0000 j= j11.8668
Carbon-13: j0.0111 jx j13.0034 j= j0.1443
11.8668 j+ j0.1443 j= j12.0111 j= jatomic jweight jof jcarbon
How jmany jelements jare jthere? jAnd jhow jmany jare jare jnaturally joccuring? j-
jANS✓✓-117 jelements, j94 jof jwhich joccur jnaturally jon jEarth.
Compounds- j- jANS✓✓-Substances jcontaining jtwo jor jmore jelements. j
- jare jdecomposed jby jchemically jreactions jrather jthan jseparated jby jphysical
jones.
Solutions- j- jANS✓✓--Are jhomogeneous jmixtures. j
-Uniform jin jtheir jcomposition. j
-Consist jof ja jsolute j(the jsubstance jthat jis jdissolved) jand ja jsolvent j(the
jsubstance jthat jdoes jthe jdissolving)
Mixtures- j- jANS✓✓-contain jtwo jor jmore jdifferent jsubstances jthat jare
jphysically jmixed jbut jnot jchemically jcombined.
j-can jbe jseparated jby jphysical jmethods j(while jcompounds jcan jnot).
Solvation- j- jANS✓✓-The jintermolecular jattraction jbetween jthe jsolvent jand jthe
jsolute.
Hydration- j- jANS✓✓-refers jto jsolutions jin jwhich jwater jis jthe jsolvent.
In jmolecular jformulas, jmolecules jare jorganized jaccording jto jthe j__________
jsystem. j- jANS✓✓-Hill jsystem. j
- jCarbon jfirst, jthen jhydrogen, jthen jthe jremaining jelements jin jalphabetical
jorder. j
- jIf jthere jare jno jcarbon jatoms jthan jall jare jorganized jalphabetically. j
*exceptions: j
j-Oxygen jis jusually jlisted jlast jin joxides
