Olympiad/HOTS Corner

Seema conducts an experiment to test the nature of four different samples. She noted down her observation in the given table.

Which of the following conclusion can be drawn from the experiment?

Smitha took a spoon of turmeric and made a paste by adding little water to it. She cut thin strips of paper and applied this paste on them. After drying, she put a few drops of the given samples solutions $\left(\mathrm{i}\right)-\left(\mathrm{iv}\right)$ on these strips. What would be the changes in the colour she observed?

$\left(\mathrm{i}\right)$ Amla juice

$\left(\mathrm{ii}\right)$ Lime water

$\left(\mathrm{iii}\right)$ Common salt solution

$\left(\mathrm{iv}\right)$ Baking soda solution

During the science activity, class teacher arranged the test tube as shown and asked the students to predict the effect of various indicators on the given solutions.

Which of the following statements are correct?

$\mathrm{I}.$ Turmeric solution will turn red in test tubes $1$ and $4$.

$\mathrm{II}.$ Methyl orange will turn yellow in test tubes $1$ and $3$.

$\mathrm{III}.$ China rose indicator will turn dark pink in test tube $2$.

$\mathrm{IV}.$ Blue litmus solution will turn red in test tubes $1$ and $4$.

Shruti tested the nature of a few common substances with the help of some indicators. The indicators used and the changes she observed are as follows:

Substances present in test tube $\mathrm{I}, \mathrm{II}, \mathrm{III},$ and $\mathrm{IV}$ are respectively.

Fill in the blanks in the given table by choosing an appropriate option.

Consider the following statements:

$\mathrm{I}.$ Baking soda is an acidic salt, whereas common salt is a basic salt.

$\mathrm{II}.$ The water extract of spinach does not change the colour of the red litmus solution.

$\mathrm{III}.$ Organic matter neutralises the acidic nature of the soil.

$\mathrm{IV}.$ Lime water is acidic in nature.

The incorrect statement(s) is/are:

Deepak found that the soil in his field is too basic in nature, while Karan used excessive chemical fertilisers in his fields. What should they add to their fields to improve the quality of the soil?

''We have to get the problem of acid rain under control. We must do whatever it takes to get the $\mathrm{pH}$ down to zero.'' The quote is: