Acids And Bases-1

QUESTION: 1

An aqueous solution turns red litmus solution blue. Excess addition of which of the following solution would reverse the change ?

A.
Baking powder
B.
Lime
C.
Ammonium hydroxide solution
D.
Hydrochloric acid

Solution:

As the solution turns red litmus solution blue, it must be basic. To reverse the change, we must add an acid.

QUESTION: 2

NaOH is obtained by electrolysis of

A.
Aq. solution of NaCl
B.
Aq. Na₂CO₃
C.
Aq. NaHCO₃
D.
Molten NaCl

Solution:

2NaCl + 2H₂O ------- > 2NaOH + H₂ + Cl₂

QUESTION: 3

One of the constituents of baking powder is sodium hydrogencarbonate, the other constituent is

A.
hydrochloric acid
B.
tartaric acid
C.
acetic acid
D.
sulphuric acid

Solution:

To decompose sodium hydrogencarbonate, we require an acid. Since it is used in food, we use a mild organic acid which is not toxic to human system.

QUESTION: 4

Lime water reacts with chlorine to form

A.
CaCl₂
B.
CaOCl₂
C.
Ca(CIO₃)₂
D.
CaO₂Cl₂

Solution:

Ca(OH)₂ + Cl₂ → CaOCl₂+ H₂O

QUESTION: 5

A sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH paper yellowish-orange. Which of the following would change the colour of this pH paper to greenish-blue ?

A.
Lemon juice
B.
Vinegar
C.
Common salt
D.
An antacid

Solution:

Only a basic solution will change the colour of pH paper to greenish-blue.

QUESTION: 6

Ag₂S reacts with H₂S0₄ to form

A.
AgS0₄
B.
Ag₂S0₄ + H₂S
C.
Ag₂0 + H₂S
D.
Ag0H + H₂S

Solution:

Ag₂S + H₂S0₄ → Ag₂S0₄ + H₂S

QUESTION: 7

Which of the following statements are true for acids ?

A.
Bitter and change red litmus to blue.
B.
Sour and change red litmus to blue.
C.
Sour and change blue litmus to red.
D.
Bitter and change blue litmus to red.

Solution:

Acids possess sour taste and turn blue litmus paper red.

QUESTION: 8

pH of H₂0 is

A.
7
B.
8
C.
9
D.
10

Solution:

pH of H₂0 is 7 because it is neutral.

QUESTION: 9

Which of the following are present in a dilute aqueous solution of hydrochloric acid ?

A.
H₃O⁺ + Cl^-
B.
H₃O⁺ + CH^-
C.
Cl^- + OH^-
D.
Unionised HCl

Solution:

Hydrochloric acid ionises as follows :
HCl→ H⁺ +Cl^-
H⁺ ions combine with water molecules to form H₃0⁺. Therefore, the ions present in dilute aqueous solution of hydrochloric acid are H₃0⁺ and Cl^-.