Consider the following statements:
(i) Both acids and bases change colour of all indicators.
(ii) If an indicator gives a colour change with an acid, it does not give a change with a base.
(iii) If an indicator changes colour with a base, it does not change colour with an acid.
(iv) Change of colour with an acid and a base depends on the type of the indicator.
Which of the above statements is/are correct?

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(a)

Only (iv)

(b)

(i) and (iv)

(c)

(ii) and (iii)

(d)

All of these

Turmeric is a natural indicator. On adding its paste to acid and base separately, which colours would be observed?

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(a)

Yellow in both acid and base

(b)

Yellow in acid and red in base

(c)

Pink in acid and yellow in base

(d)

Red in acid and blue in base

Phenolphthalein is a synthetic indicator and its colours in acidic and basic solutions respectively are

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(a)

red and blue

(b)

blue and red

(c)

pink and colourless

(d)

colourless and pink

When the soil is too basic, plants do not grow well in it. To improve its quality, what must be added to the soil?

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(a)

Organic matter

(b)

Quicklime

(c)

Slaked lime

(d)

Calamine solution

Neutralisation reaction is a

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(a)

physical and reversible change

(b)

physical change that cannot be reversed

(c)

chemical and reversible change

(d)

chemical change that cannot be reversed

Sting of an ant contains

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(a)

Vinegar

(b)

Common salt

(c)

Formic acid

(d)

Milk of magnesia

Stomach secretes:

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(a)

HCl

(b)

H₂SO₄

(c)

CH₃COOH

(d)

NaOH

Raw mango is sour in taste due to presence of

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(a)

Tartaric acid

(b)

Citric acid

(c)

Formic acid

(d)

Oxalic acid

Sodium hydroxide is

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(a)

A base

(b)

An alkali

(c)

Bitter in taste

(d)

All of these

The medicine used for treating indigestion is:

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(a)

Antibiotic

(b)

Anti-acid

(c)

Antacid

(d)

Analgesic

Acid + Base \(\longrightarrow\) _____________ + Water

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(a)

salt

When an acid mixed with a base, a __________ reaction takes place.

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(a)

neutralisation

Acetic acid is present in __________ while __________ is present in lemon.

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(a)

vinegar, citric acid

_____________is used to remove acidity of solids

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(a)

Slaked lime

Ammonium chloride is an example of _____________salt

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(a)

acidic

Lime water turns red litmus blue.

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(a) False

(b) True

Common salt dissolved in water turns blue litmus red.

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(a) True

(b) False

Phenolphthalein is a natural indicator.

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(a) False

(b) True

Calamine can be used to treat ant's sting.

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(a) False

(b) True

Lemon water is basic in nature.

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(a) True

(b) False

What are acids?

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(a)

Substances which are sour in taste are called acids.

What are bases?

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(a)

Substances which are bitter in taste and soapy to touch are called bases

What are indicators?

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(a)

Indicators are the substances that are used to test the acidity or basicity of a substance

Name two natural occurring indicators

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(a)

Litmus and turmeric are natural occurring indicators

Name two substances which changes red litmus blue.

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(a)

Sodium hydroxide, magnesium hydroxide