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Each part: 1 Mark
Bases turn red litmus blue, while acids turn blue litmus red.
a) Since calcium hydroxide is a base, the red litmus will turn blue.
b) No color change will take place as sodium chloride is a neutral salt.
c) Since lemon juice contains citric acid, the bluelitmuspaper will becomered.
d) No color change will take place as distilled water is neutral by nature.
e) Turmeric powder is yellow in color and it turns pink when treated with a basic solution. Hence here the turmeric will turn pink as sodium hydroxide is a base.

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Each point: 1 Mark
a) True.Olfactory indicators respond to acid or base by change in smell.
b) False. When an aqueous solution of shampoo is mixed with extract of red cabbage, the solution turns green. This is because the shampoo is basic in nature.
c) False. Methyl orange is an artificial indicator

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Description: 1 Mark
Use: 1 Mark
Examples: 1 Mark
Substances that exhibit a change of colour or odourwhenadded toacidic, basic and neutral solutions are called indicators.
Visual indicators show different colours in presence ofan acidicand a basic solution. Similarly, olfactory indicators exhibit different odour when added to acids or bases. Thus, they help us in deciding whether a given solution is acidic or basic in nature.
Some of the naturally occurring indicators are china rose petals, litmus, turmeric, etc.

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Solution: 1 Mark
Verification: 1 Mark
Vinegar is made primarily from acetic acid which makes it acidic.
Litmus paper can be used to verify whether vinegar is acidic/basic/neutral.
Vinegar changes the colour of blue litmus to red. This proves that vinegar is acidic.

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Each part: 1 Mark
(a) Ammonia turns red litmus blue so it is basic in nature.
(b)If blue litmus paper is dipped in a solution and it would remain blue then the solution may be basic or neutral in character.
Blue litmus paper does not change its colour with basic solution and neutral solution.

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Correct answer: 1 Mark
Reason: 1 Mark
Vinegar, formic acid and curd are all acidic in anture.
Calamine is the odd one.
It is the only basic substance in the given list. This is the reason why it used as a remedy for ant bites.

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Amino acids are present in proteins.

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Why: 1 Mark
Treatment process: 1 Mark
Type of reaction: 1 Mark
We need to treatfactory wastes before they are allowed to flow into water bodies because they contain acids. If they are allowed to flow into the water bodies, the acids will kill the fishes and other organisms.
We use bases to neutralizethe factory wastes.
It is a type of neutralization reaction because an acid is treated with a base.

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When: 1 Mark
Why: 1 Mark
Explanation: 1 Mark
We add organicmatter to the soil when the soil is basic.
Organic matter release acids into the soil.The bases which are present get neutralized. We add organic matter because if the soil too basic in nature, the plants do not grow well.

Answer: Option A. -> True
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A
A chemical indicator is any substance that gives a visible sign, usually by a colour change, of the presence or absence of a threshold concentration of a chemical species, such as an acid or an alkali in a solution.