G2 Science (Chemistry) Qualitative Analysis · question set

Try K223/K225 Qualitative Analysis exam-style questions. Covers only the prescribed tests and positive observations for carbon dioxide, hydrogen and oxygen. Cation, anion and other gas tests are excluded.

SEC G2 Science Chemistry component 2027

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Which observation is the positive test for carbon dioxide?

Limewater turns milky
A glowing splint relights
Damp red litmus turns blue
A lighted splint gives a pop

Which test and result identify hydrogen?

Apply a lighted splint; the gas burns with a pop
Insert a glowing splint; it relights
Use damp red litmus; it turns blue
Bubble through limewater; it turns milky

Which test and result identify oxygen?

Insert a glowing splint; it relights
Apply a lighted splint; the gas gives a pop
Use damp litmus; it is bleached
Bubble through limewater; it turns milky

Which complete statement describes a positive test for carbon dioxide?

Bubble the gas through limewater; the limewater turns milky
Insert a glowing splint; the gas burns with a pop
Apply a lighted splint; the splint relights
Bubble the gas through water; the water turns white

A gas turns limewater milky. Which line correctly separates observation from inference?

Observation: limewater turns milky; inference: carbon dioxide is present
Observation: carbon dioxide is present; inference: limewater turns milky
Observation: a glowing splint relights; inference: carbon dioxide is present
Observation: the gas is acidic; inference: hydrogen is present

Why should only a small sample of hydrogen be tested with a lighted splint?

Hydrogen is flammable, so a small sample limits the combustion hazard
A large sample would turn into oxygen
Only small samples can relight a glowing splint
Hydrogen becomes non-flammable in a large sample

A glowing splint relights in an unknown gas. What is the observation and inference?

The glowing splint relights; oxygen is present
The gas gives a pop; carbon dioxide is present
Limewater turns milky; oxygen is present
The lighted splint goes out; hydrogen is present

Which substance makes limewater appear milky during a positive carbon dioxide test?

Insoluble calcium carbonate
Dissolved calcium metal
Hydrogen gas bubbles
Solid calcium oxide

Which answer gives both the correct hydrogen procedure and positive result?

Apply a lighted splint to a small sample; the gas burns with a squeaky pop
Insert a glowing splint; the gas burns with a squeaky pop
Apply a lighted splint; the splint relights
Bubble through limewater; the gas burns with a squeaky pop

Which answer gives both the correct oxygen procedure and positive result?

Insert a glowing splint; the splint relights
Apply a lighted splint; the gas gives a squeaky pop
Insert a lighted splint; limewater turns milky
Bubble through limewater; the splint relights

A glowing splint does not relight in an unknown gas. Why does this not prove the gas is hydrogen?

Many gases give a negative oxygen test; hydrogen still needs its own positive lighted-splint test
Every gas except oxygen is hydrogen
Hydrogen is identified by limewater turning milky
A negative result is always more reliable than a positive result

Three samples are known to be carbon dioxide, hydrogen and oxygen. Which set of positive results identifies all three?

Milky limewater; squeaky pop with a lighted splint; relit glowing splint
Relit glowing splint; milky limewater; bleached dry litmus
Squeaky pop with a glowing splint; relit lighted splint; clear limewater
Blue damp red litmus; yellow precipitate; milky limewater

G2 Science (Chemistry) Qualitative Analysis · question set

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