A few drops of universal indicator is added to four colourless solutions, A, B, C and D having pH 2, 10, 9 and 7, respectively. Which of the following test tube is labelled with incorrect colour.

1. A
2. B
3. C
4. D

In the electrolysis of alumina, cryolite is added to

1. lower the melting point of alumina
2. decrease the electrical conductivity
3. minimize the anode effect
4. remove impurities from alumina

2 mL of ethanoic acid was taken in test tube I and test tube II each. A red litmus paper was introduced in test tube I and a pH paper was introduced in test tube II. The experiment was performed by four students W, X, Y and Z; and they reported their observation as given in the table.

Which students observation is correct?

1. W
2. X
3. Y
4. Z

Ammonia can be obtained by adding water to

1. ammonium chloride
2. ammonium nitride
3. magnesium nitride
4. magnesium nitrate