Indicators and the pH scale — Question Bank (Cambridge) — Cambridge IGCSE Physics 0625 Revision Notes & Topical Questions

Cambridge Lower Secondary Stage 7

Question 1
Paper Ref: 0620/21_Summer_2026_Q19

Sodium hydroxide forms an alkaline solution.
Which indicator turns yellow when added to this solution?
A litmus
B- methyl orange
>)
thymolphthalein
D_ universal indicator

Options:
A
B
C
D
Correct Key: B

Question 2
Paper Ref: 0620/12_Spring_2021_Q18

Which property is shown by the alkali sodium hydroxide?
A
B
Cc
D
It has a pH less than pH 7.
It produces a gas when it is warmed with ammonium chloride.
It turns blue litmus red.
It turns universal indicator green.

Options:
A
B
C
D
Correct Key: B

Question 3
Paper Ref: 0620/23_Summer_2014_Q21

Only two elements are liquid at 20°C. One of these elements is shiny and conducts electricity.
This suggests that this element is a …… Vee and therefore its oxide is …… Qo.
Which words correctly complete gaps 1 and 2?
1 2
A metal acidic
B metal basic
Cc non-metal acidic
D non-metal basic

Options:
A
B
C
D
Correct Key: B

Question 4
Paper Ref: 0620/21_Summer_2014_Q20

Only two elements are liquid at 20°C. One of these elements is shiny and conducts electricity.
This suggests that this element is a …… Vee and therefore its oxide is …… Qo.
Which words correctly complete gaps 1 and 2?
metal acidic
metal basic
non-metal acidic
non-metal basic

Options:
A
B
C
D
Correct Key: B

Question 5
Paper Ref: 5129/11_Winter_2020_Q19

Which statement describes a solution that contains hydrogen ions?
A
B
Cc
D
It reacts with acids to produce salt.
It reacts with ammonium chloride to produce a gas which turns red litmus paper blue.
It reacts with metals to produce a gas which pops with a lighted splint.
It turns red litmus paper blue.

Options:
A
B
C
D
Correct Key: C

Question 6
Paper Ref: 0620/11_Summer_2025_Q18

A mixture of two substances, R and §S, is heated gently.
The damp red litmus paper turns blue.
damp red
ae litmus paper
Rands
gentle heat
What are R and S?
R Ss
A basic oxide ammonium chloride
B a basic oxide sodium nitrate
Cc an acidic oxide ammonium chloride
D an acidic oxide sodium nitrate

Options:
A
B
C
D
Correct Key: A

Question 7
Paper Ref: 0620/23_Summer_2014_Q25

Aqueous sodium hydroxide is added to solid X and the mixture is heated.
A green precipitate is formed and an alkaline gas is given off.
Which ions are present in X?
NH,” and Fe”*
NH,” and Fe**
OH and Fe**
D OH -andFe*
oO W

Options:
A
B
C
D
Correct Key: A

Question 8
Paper Ref: 5129/12_Winter_2021_Q19

When sulfur dioxide dissolves in water an acidic solution is formed.
Which ion causes the solution to be acidic?
A the hydrogen ion
B the hydroxide ion
C the oxide ion
D
the sulfate ion

Options:
A
B
C
D
Correct Key: A

Question 9
Paper Ref: 0620/23_Summer_2015_Q16

Hydrochloric acid is used to clean metals.
The acid reacts with the oxide layer on the surface of the metal, forming a salt and water.
Which word describes the metal oxide?
A alloy
B_ base
Cc element
D
indicator

Options:
A
B
C
D
Correct Key: B

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