Chemistry Past Questions and Answers

A stream of air was successively passed through three tubes X, Y and Z containing a concentrated aqueous solution of KOH, red hot copper powder and fused calcium chloride respectively. What was the composition of the gas emanating from tube Z?

In the purification of town water supply, alum is used principally to?

Which of the following water samples will have the highest titre value when titrated for the Ca<sup style='font-size: smaller;'>2+</sup> ions using soap solution?

Oil spillage in ponds and creeks can be cleaned up by?

The solubility of Na<sub style='font-size: smaller;'>3</sub>AsO<sub style='font-size: smaller;'>4</sub>(H<sub style='font-size: smaller;'>2</sub>O)<sub style='font-size: smaller;'>12</sub> is 38.9g per 100g H<sub style='font-size: smaller;'>2</sub>O. What is the mass percentage of Na<sub style='font-size: smaller;'>3</sub>AsO<sub style='font-size: smaller;'>4</sub> in the saturated solution? <br/>(As = 75, Na = 23, O = 16, H = 1)