Question 13

State whether the following statements are true or false. Correct the false statements.
(a) All substances are either acidic or basic.
(b) A compound if acidic will turn all indicators red
(c) Lime water turns red litmus blue
(d) Common salt dissolved in water turns blue litmus red
(e) Phenolphthalein is a natural indicator
(f) Calamine can be used to treat ant’s sting
(g) Lemon water is basic in nature

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Solution

(a) False. Substances can be neutral as well.
(b) False. Acids do not turn all indicators red. E.g: china rose indicator turns to dark pink on the addition of an acidic solution.
(c) True, lime water is basic.
(d) False. It does not change the colour of litmus at all since both are neutral in nature.
(e) False. It is a man-made indicator.
(f) True, calamine is basic in nature while ant's sting is acidic. Hence it can be used to treat an ant's sting.
(g) False. It is acidic in nature

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Similar questions

State whether the following statements are true or false. Correct the false statements. [5 MARKS]
(a) All substances are either acidic or basic.
(b) A compound if acidic will turn all indicators red.
(c) Lime water turns red litmus blue.
(d) Common salt dissolved in water turns blue litmus red.
(e) Phenolphthalein is a natural indicator.

Mark ‘T’ if the statement is true and ‘F’ if it is false:

(i) Nitric acid turns red litmus blue. (T/F)

(ii) Sodium hydroxide turns blue litmus red. (T/F)

(iii) Sodium hydroxide and hydrochloric acid neutralise each other and form salt and water. (T/F)

(iv) Indicator is a substance which shows different colours in acidic and basic solutions. (T/F)

(v) Tooth decay is caused by the presence of a base. (T/F)

Q58) Consider the following statements about acid-base indicators.

i) Phenolphthalein gives a pink colour if the solution is acidic.

ii) China rose indicator turns acidic solutions to dark pink.

iii) Blue litmus turns red for a basic solution.

Which of the above statements are true?

Mark ‘T’ if the statement is true and ‘F’ if it is false

(i) Nitric acid turn red litmus blue. (T/F)

(ii) Sodium hydroxide turns blue litmus red. (T/F)

(iii) Sodium hydroxide and hydrochloric acid neutralize each other and form salt and water. (T/F)

(iv) Indicator is a substance which shows different colours in acidic and basic solutions. (T/F)

(v) Tooth decay is caused by the presence of a base. (T/F)

Q. Write True (T) or False (F) against the following statements in the given brackets:
1. Acids corrode metals. ( )
2. Distilled water is a neutral substance. ( )
3. Sodium hydroxide turns blue litmus red. ( )
4. The stings of bees contain an acid. ( )
5. Milk of magnesia is used in antacids. ( )

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Indicators and Universal Indicator

Standard VII Chemistry

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