Indicators & pH
What pH value is neutral?
A) 0
B) 7
C) 14
D) 1
B) 7
Neutralisation always produces:
A) Salt only
B) Salt + water
C) Acid + alkali
D) Gas
B) Salt + water
Why do we use a burette in titration?
A) To measure exact volume of acid/base
B) To mix solutions faster
C) To heat the solution
D) To see the indicator clearly
A) To measure exact volume of acid/base
A solution turns red litmus paper blue. What is it?
A) Acid
B) Alkali
C) Neutral
D) Salt
B) Alkali
Which indicator turns pink in alkalis?
A) Methyl orange
B) Litmus
C) Phenolphthalein
D) Universal indicator
C) Phenolphthalein
What is formed when hydrochloric acid reacts with sodium hydroxide?
A) Sodium chloride + water
B) Sodium + water
C) Hydrogen + sodium chloride
D) Salt only
A) Sodium chloride + water
What is the “rough titre”?
A) A first estimate to find approximately how much acid/base is needed
B) The final accurate volume
C) The leftover solution
D) The colour of the indicator
A) A first estimate to find approximately how much acid/base is needed
Which statement is true?
A) All acids are strong
B) All alkalis are weak
C) pH 7 = neutral
D) pH 14 = acidic
C) pH 7 = neutral
What colour does methyl orange turn in an acid?
A) Blue
B) Red
C) Green
D) Yellow
B) Red
Which of these is an alkali?
A) HCl
B) NaOH
C) H₂SO₄
D) CO₂
B) NaOH
Why do we repeat a titration after the rough titre?
A) To make the solution more colourful
B) To get a more accurate measurement of acid/base volume
C) To neutralise the solution again
D) To increase the amount of salt made
B) To get a more accurate measurement of acid/base volume
Hydrochloric acid reacts with magnesium. What gas is produced?
A) Oxygen
B) Carbon dioxide
C) Hydrogen
D) Chlorine
C) Hydrogen
A solution has pH 3. Which statement is correct?
A) Neutral
B) Weakly alkaline
C) Strongly acidic
D) Weakly acidic
C) Strongly acidic
What is the purpose of using an indicator in neutralisation?
A) To see the exact point when the acid is neutralised
B) To make the solution colorful
C) To speed up the reaction
D) To dissolve salts faster
A) To see the exact point when the acid is neutralised
After a titration is complete, how do we obtain the salt?
A) Freeze the solution
B) Evaporate the water to crystallise the salt
C) Pour it down the sink
D) Add more acid
B) Evaporate the water to crystallise the salt
Universal indicator shows a solution is dark green. Which statement is correct?
A) Strong acid
B) Neutral or weak acid/alkali
C) Strong alkali
D) Cannot tell
B) Neutral or weak acid/alkali
Which of these is true about the pH scale?
A) Higher numbers = more acidic
B) Lower numbers = more acidic
C) 7 = strong alkali
D) 7 = strong acid
B) Lower numbers = more acidic
Which equation is correctly balanced?
___ H₂SO₄ + ___ NaOH → ___ Na₂SO₄ + ___ H₂O
A) 1 + 1 → 1 + 1
B) 1 + 2 → 1 + 2
C) 2 + 1 → 1 + 2
D) 1 + 2 → 1 + 1
B) 1 + 2 → 1 + 2
A student overshoots the endpoint in titration. What happens?
A) The solution is neutral
B) The solution becomes acidic or alkaline, making an impure salt
C) More salt is produced
D) The solution disappears
B) The solution becomes acidic or alkaline, making an impure salt
A student adds universal indicator to a solution and sees the colour is orange. The student says, “This solution must be neutral.” Why is this statement wrong?
A) Orange is the colour for a strong alkali, not neutral
B) Orange indicates a weak acid, not neutral
C) Orange indicates a weak alkali, not neutral
D) The solution is definitely neutral
B) Orange indicates a weak acid, not neutral