What is indicator? Give the names of any two indicators and what is the effect of acids and bases on them.

What is an alkali? Do basic solutions also have ${\mathrm{H}}^{+}$(aq) ions? If yes, then why are these basic? 

What is meant by strong acids and weak acids?

Classify the following into strong acids and weak acids:
$\mathrm{H}\mathrm{C}\mathrm{l}, \mathrm{C}{\mathrm{H}}_3\mathrm{C}\mathrm{O}\mathrm{O}\mathrm{H}, {\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4, \mathrm{H}\mathrm{N}{\mathrm{O}}_3, {\mathrm{H}}_2\mathrm{C}{\mathrm{O}}_3, {\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_3$