• Fill half a beaker with water.
• Put a watch glass on the mouth of the beaker.
• Put few drops of ink on the watch glass.
• Now start heating the beaker. We do not want to heat the ink directly. You will see that evaporation is taking place from the watch glass.
• Continue heating as the evaporation goes on and stop heating when you do not see any further change on the watch glass.
• Observe carefully and record your observations.
1. What do you think has got evaporated from the watch glass?
2. Is there a residue on the watch glass?
3. What is your interpretation? Is ink a single substance (pure) or is it a mixture?
NCERT Class 9th Science Ch 2 Is Matter Around Us Pure