Q67. Saloni took a piece of burning charcoal and collected the gas evolved in a test tube.
(a) How will she find the nature of the gas?
(b) Write down word equations of all the reactions taking place in this process.
Q68. When an iron knife is kept dipped in blue copper sulphate solution the solution changes to light green. Why?
Or
What happens when a piece of iron metal is placed in copper sulphate solution name the type of reaction involved?
Q69. Explain how metals and non-metals produce oxides with different characteristics.