Give the characteristic tests for the following gases:
$(a)$ $O_2$
$(b)$ $H_2$

Which among the following statement$(s)$ is(are) true? Exposure of silver chloride to sunlight for a long duration turns grey due to
$(i)$ the formation of silver by decomposition of silver chloride
$(ii)$ sublimation of silver chloride
$(iii)$ decomposition of chlorine gas from silver chloride
$(iv)$ oxidation of silver chloride

How will you test whether the gas evolved in a reaction is hydrogen?

Write the balanced chemical equation for the following and identify the type of reaction in each case.
$(a)$ Potassium bromide $(aq) +$ Barium iodide $(aq) \rightarrow$ Potassium iodide $(aq) +$ Barium bromide $(s)$
$(b)$ Zinc carbonate $(s) \rightarrow$ Zinc oxide $(s) +$ Carbon dioxide $(g)$
$(c)$ Hydrogen $(g) +$ Chlorine $(g) \rightarrow$ Hydrogen chloride $(g)$
$(d)$ Magnesium $(s) +$ Hydrochloric acid $(aq) \rightarrow$ Magnesium chloride $(aq) +$ Hydrogen $(g)$

Which of the following is(are) an endothermic process(es)?
$(i)$ Dilution of sulphuric acid
$(ii)$ Sublimation of dry ice
$(iii)$ Condensation of water vapours
$(iv)$ Evaporation of water

What happens when sulfur trioxide reacts with water?