Consider the following statements about bases.
I. Bases have bitter taste and soapy touch.
II. With carbon dioxide, they form salt and water. rau
III. The gas evolved with zinc metal extinguishes a lightning splinter
The correct statement(s) is/are
(a) I and II
(b) II and III
(c) Only I
(d) All of these
Answers
i. Bases tend to taste bitter and feel soapy. [Bases are bitter and soapy to touch]
ii.ii. Like acids, aqueous basic solutions conduct electricity, and are identified as electrolytes.
iii.iii. Bases react with acid to produce a salt and water. [Neutralization]
iv.iv. Bases turn blue, indigo, violet (three) different colours.
The correct statements are:
I. Bases have a bitter taste and soapy touch.
II. With carbon dioxide, they form salt and water.
III. The gas evolved with zinc metal extinguishes a lightning splinter.
(option d)
Characteristics of Bases
- Bases are substances that turn red litmus paper blue.
- According to Arrhenius' theory, a base is a substance that increases the hydroxyl(OH⁻) concentration in a solution.
- Bases are bitter in taste and slippery or soap-like to touch.
The reaction of Bases with Carbon Dioxide
- Bases react with carbon dioxide to form metal carbonate and water.
- For example, let us consider the reaction of sodium hydroxide with carbon dioxide.
NaOH + CO₂ → Na₂CO₃ + H₂O
(sodium hydroxide) (sodium carbonate)
The reaction of Bases with Metals
- Bases react with metals to give metal salt and evolve hydrogen gas.
- For example, let us consider the reaction of Zinc with NaOH.
2 NaOH + Zn → Na₂ZnO₂ + H₂
(sodium zincate)
- The hydrogen evolved can extinguish a burning splinter with a pop sound.
Hence, the correct option is (d) All of these.