A few question need help
1.
Gas
Percentage by volume
Boiling
point
Nitrogen
78%
-196
Oxygen
21%
-183
Argon
About
1%
-190
a)State one use of oxygen
b)The three main gases can be separated by fractional
distillation of liquid air. Which gas will come out of the
fractionating column first?
c)Briefly explain how the air is liquefied in the separation
process mentioned in (b)
2) Three test tube are left for several day.
Test tube
1
Test tube
2
Test tube
3
Water,iron
nail,air
Iron nail,Solid calium chloride
Iron nail,oil
In which of the test tube would rusting take place? Explain briefly
your choice.
3)In another experiment.a student heated a small amount of
copper(II) nitrate crystal in a test tube. Colourless droplets
collected at the mouth of the tube. On the further heating,a brown
gas was given off. A glowing splint was held at the mouth of the
test tube.
(a) What colour was the copper(II)nitrate before heating?
b) What are the colourless droplets?
c)What happens to the glowing splint?
d)Name the brown gas given off.
4a)Name the compound of sulphur firned when the coal is
burnt.
ai) Write a balanced chemical wquation for the formation of the
compund in (a).
aii)Bane the acid formed when this compund reacts with
rainwater.
b)What effect does 'acid rain' on
i)plants
ii)buildings