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Five solutions A,B,C,D and E when tested with universal indicator showed pH as
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4,1,11,7 and 9, respectively. Which solution is
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(a) neutral?
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(b) strongly alkaline?
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(c) strongly acidic?
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(d) weakly acidic?
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(e) weakly alkaline?
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Arrange the pH in increasing order of hydrogen-ion concentration.
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Answer:
**

We know that,

pH of a neutral solution = 7

pH of an acidic solution < 7

pH of a basic solution > 7

The lower the pH of a solution is than 7, the more is it’s acid concentration

The higher the pH of a solution is than 7, the more is it’s base concentration.

Given pH of the solutions

A - 4

B - 1

C - 11

D - 7

E - 9

Arranging in decreasing level of pH (and hence increasing level of H
^{
+
}
ion concentration. Because, more the pH, higher the acidic nature, higher the H
^{
+
}
ions concentration)

**
C>E>D>A>B
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**
(from most basic to most acidic)
**

(a) neutral

pH of D = 7

Hence, it is neutral

(b) strongly alkaline?

pH of C = 11 >> 7

It is much higher than 7, hence it’s strongly alkaline

(c) strongly acidic?

pH of B = 1 << 7

It is much lesser than 7, hence it’s strongly acidic

(d) weakly acidic?

pH of A =4 < 7

It is less than 7, hence its acidic but it is much lesser than 7 , hence it’s weakly acidic.

(e) weakly alkaline?

pH of E = 9 >7

It is more than 7, hence its basic but It is not much higher than 7, hence it’s weakly basic.