Q2 of 29 Page 73

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.

The changes observed when a litmus paper was dropped into 2ml dilute HCl. Then 2ml concentrated NaOH was added to it and stirred are:

i. With HCl, the litmus paper turns red.


ii. With NaOH, the litmus paper turns blue.


Explanation: HCl is an acid and has pH lesser than 7, thus its


colour changes to red.


NaOH is a base and has pH greater than 7, thus its colour changes to blue.



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