Chapter 2 · Acids, Bases and Salts

NCERT Class 10 Science Chapter 2 Intext Questions (Page 18)

All 1 questions of NCERT Class 10 Science Chapter 2 Intext Questions (Page 18) — Acids, Bases and Salts — in the book's order, each with its answer and a step-by-step solution.

1. Q1
   You have ​been provided with three ​test tubes. One of them ​contains distilled water and ​the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus ​paper, how ​will you identify the contents ​of each test tube?
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   Red litmus turning blue shows the base; that blue strip turns red in the acid and stays blue in distilled water.

   Red litmus paper turns blue only in a basic solution; an acidic solution and distilled water both leave it red, so red litmus alone cannot separate those two. Step 1: Dip a strip of red litmus paper into each of the three test tubes (a fresh strip for each). The tube in which the paper turns blue contains the basic solution. Step 2: The strip that has turned blue is now blue litmus paper. Cut it in two and touch it to the two remaining solutions. The solution that turns this blue paper red is the acidic solution, and the solution that leaves it blue is the distilled water. (One test in Step 2 is enough: whichever tube reacts, the third tube is the other one.)

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