Reaction of zinc metal with sodium hydroxide will lead to the formation of

1. sodium zincate
2. sodium chloride
3. zinc hydroxide
4. zinc aluminate

The reddish brown coloured gas formed when nitric acid reacts with carbon is

1. N₂O₅
2. N₂O₄
3. NO₂
4. N₂O₃

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