31.
The name of unreactive gas is

32.
The green colour seen in firework displays is due to the chloride salt of :

33.
In deep-sea diving, divers use a mixture of gases consisting of oxygen and

34.
Now-a-days yellow lamps are frequently used as street lights. Which of the following gases is used in these lamps ?

35.
Which of the following is not soluble in water ?

37.
The three elements most needed in common fertilisers are :

38.
Liquid Nitrogen boils at

39.
Which one of the following is not a fertilizer?

40.
Which of the following gases is mixed with oxygen for breathing by divers in aqua lungs?