Question

Alex had two solutions: X and Y. He added a few drops of turmeric water in solution X and observed that the solution X turned yellow in colour. On adding turmeric water to solution Y, he observed that the solution turned red in colour. From the options given below, identify the solutions that match Alex’s observations.
1)X : N H 4 C l ; Y : M g ( N O 3 ) 2
2)X : N a C l ; Y : K 2 S O 4
3)X : N a 2 C O 3 ; Y : N H 4 C l
4)X : N H 4 C l ; Y : N a 2 C O 3​

Answer 1

Answer:

Turmeric is a natural indicator which help us to identify whether a given solution is an acid, base or a neutral compound.

The indicator undergoes a colour change according to the pH of the solution.

In acidic medium turmeric is yellow in colour and in basic medium it turns to red colour.

Since in basic solutions the colour of turmeric changes from yellow to red, therefore the correct answer is option

Answer 2

The solutions X and Y are $\[N{H_4}Cl\]$ and $\[N{a_2}C{O_3}\]$ respectively. Thus, the correct option is D.

Explanation:

• Turmeric acts as a natural indicator. It can be used to test the acidity or basicity of solutions.
• It is yellow in colour and it remains yellow with neutral and acidic solutions.
• On the other hand, it turns red in colour when it comes in contact with basic solutions.
• $\[N{H_4}Cl,\,NaCl,\,Mg{(N{O_3})_2},\,{K_2}S{O_4}\]$ are all salts. Therefore, turmeric will remain yellow on coming in contact with these solutions.
• $\[N{a_2}C{O_3}\]$ is a basic salt. It acts as a weak base. Therefore, turmeric will show red colour with sodium carbonate.
• As X becomes yellow on adding turmeric, it must be a neutral or acidic solution.
• As Y becomes red on adding turmeric, it must be a basic solution.
• Therefore, according to the given options, X is $\[N{H_4}Cl\]$ and Y is $\[N{a_2}C{O_3}\]$.