Which of the following pairs of reagents react to produce hydrogen?

A mixture of calcium chloride and calcium trioxocarbonate (IV) in water can be separated by

Which of the following would dissolve in warm dilute H2SO4 without effervescence, to give a blue solution?

In which of the reactions represented by the following equations is HNO3 behaving as a typical acid?

A gas was evolved when a sample of gastric juice reacted with sodium trioxocarbonate (IV) . The gas evolved was