Q2 of 29 Page 73

Write down the changes that will be seen in each instance and explain the reason behind it.

Two drops of the indicator phenolphthalein were added to 10ml solution of sodium hydroxide.

The change observed when two drops of the indicator phenolphthalein was added to 10ml solution of sodium hydroxide is:

The solution changes from colorless to dark pink in colour.


Explanation: Phenolphthalein is a basic indicator.


i. When it is mixed with any acid, it remains colourless.


ii. When mixed with any base, its colour changes to pink. NaOH is a base.


Thus, the solution becomes dark pink in colour.


More from this chapter

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1

Identify the odd one out and justify.

A. Chloride, nitrate, hydride, ammonium


B. Hydrogen chloride, sodium hydroxide, calcium oxide, ammonia


C. Acetic acid, carbonic acid, hydrochloric acid, nitric acid


D. Ammonium chloride, sodium chloride, potassium nitrate, sodium sulphate


E. Sodium nitrate, sodium carbonate, sodium sulphate, sodium chloride


F. Calcium oxide, magnesium oxide, zinc oxide, sodium oxide.


G. Crystalline blue vitriol, crystalline common salt, crystalline ferrous sulphate, crystalline sodium carbonate.


H. Sodium chloride, potassium hydroxide, acetic acid, sodium acetate.

 2

Write down the changes that will be seen in each instance and explain the reason behind it.

50ml water is added to 50ml solution of copper sulphate.

 2

Write down the changes that will be seen in each instance and explain the reason behind it.

Two or three filings of copper were added to 10ml dilute nitric acid and stirred.

 2

Write down the changes that will be seen in each instance and explain the reason behind it.

A litmus paper was dropped into 2ml dilute HCl. Then 2ml concentrated NaOH was added to it and stirred.