3.
Five solutions have been labelled as A, B, C, D & E. They have been tested with
four indicators. The observations have been recorded in the following table.
Think and answer the questions that follow:
Solution
Methyl orange Phenolphthalein
Blue litmus
Red litmus
Red
A
Colourless
Red
Red
B
Red
Colourless
Red
Red
C
Yellow
Pink
Blue
Blue
D
Orange
Colourless
Blue
Red
E
Red
Colourless
Red
Red
(a) Which solution is a base? Which solution is neutral? How many
acids have been tested?
(b) What would be the colour of turmeric paper indicator in solution C?
(c) Which of the following solutions can be used for neutralization?
(i)
A&B
(ii)
B&C
C&D
(iv)
D& E?
Acti
Go to
Answers
Answer:
Answer (a) :
Solution C is a base . We are saying that it is a base because it is turning pink under the phenolphthalein test and only bases turn pink under the phenolphthalein test . It is also turning yellow under the methyl orange test which is another sign that it is a base . Another reason we are saying that solution C is a base is that red litmus turns blue when dipped in it , which can only happen if the solution is basic in nature and the blue litmus paper stays blue when kept on it , which confirms that solution C is a base . Solution D is neutral in nature because methyl orange remains orange when mixed with it . Another reason is that it remains colourless under the phenolphthalein solution which is another sign it is a neutral solution . Solution D remains red in red litmus paper and blue in blue litmus paper , which can only happen if the solution is neutral in nature . Hence , all the above mentioned reasons or signs prove that solution D is a neutral solution . Three acids have been tested . The solutions which are acidic in nature are - Solution A , Solution B and Solution E . We are saying that all these are acids because :
1) They all become colorless in a phenolphthalein solution , which is a sign that they are acids .
2) Red litmus stays red when dipped on them , which is also a sign that they are acidic in nature .
3) They turn red under the methyl orange test , which can only happen if they are acidic in nature .
4) Blue litmus paper turns red which confirms the fact that solution A , B and E are acids .
Answer (b) :
We know that Solution C is a base and turmeric indicators turn red when dipped into a base . Hence , we can confirm that the colour of the turmeric paper indicator in Solution C will be red .
Answer (c) :
(ii) B & C
We know that neutralization happens when an acid and base comes in contact with each other and diminishes each other's properties in the process , resulting in the formation of salt , heat and water . So we need an acid and a base to do neutralization , which cannot be done with solution A & B since both of them are acids . This process can also not take place in solution C & D since one is acidic and the other is basic . This process can also take place in D and E which is neutral and basic . The only possiblity is Solution B & C since solution B is basic and Solution C is acidic , which means they are capable of doing neutralization . Hence the correct answer will be (ii)B&C .
Hope you find my answer useful!!!