Question

Four test-tubes A, B, C & D containing milk of magnesia, baking powder, vinegar &
water respectively. What change is expected when red & blue litmus paper is immersed in
these test tubes?
Colour change in red litmus Colour change in blue litmus
Test-Tube Solution
paper
paper
A
Milk of magnesia
B
Baking powder
с
Vinegar
D
Water​

Answer 1

Given:

Four test-tubes A, B, C & D containing milk of magnesia, baking powder, vinegar & water respectively.

To find:

Change is expected when red & blue litmus paper is immersed in these test tubes.

Solution:

I will try to give the answer in a tabular form:

• Any acidic substance will turn blue litmus red.

• Any basic substance will turn red litmus blue.

$\begin{array}{|c|c|c|}\cline{1-3}Substance & Blue\:Litmus & Red\: Litmus\\\cline{1-3}Milk\:of\:magnesia & No\:change & Turns\:blue\\\cline{1-3}Baking\:Powder & No\:change & Turns\:blue\\\cline{1-3}Vinegar & Turns\:red & No\:change\\\cline{1-3}Water & No\:change & No\:change\\\cline{1-3}\end{array}$

This proves that:

• Vinegar is acidic.

• Milk of Magnesia and Baking Powder is basic.

• Water is neutral.

Answer 2

A blue litmus paper is turned red by an acid substance and a red litmus paper is turned blue by basic substances.

Explanation:

• A blue litmus paper is turned red by an acid substance and a red litmus paper is turned blue by basic substances.
• Milk of magnesia has no effect on blue but it will turn red into blue.
• Baking powder will turn red into blue and has no effect pon blue paper.
• Vinegar turns blue into red and no change in red litmus paper.
• Water has no change on both litmus paper because it is neutral.