What is Hydrochloric acid (hcl) dissociates completely into an h plus ion and a cl- ion when dissolved in water?

First of all the formula for hydrochloric acid is 'HCl'. NOT 'hcl'. For single letter symbols it is ALWAYS a CAPITAL letter ; hence hydrogen is 'H'. For two letter symbols , the first letter is a CAPITAL letter and the second letter is lower case., hence chlorine is 'Cl;. This is the recognised international standard.

To answer you question .

HCl is hydrogen chloride , which is a gas. However, it readily dissolves in water to form hydrochloric acid. As it dissolves it form the ions 'H^(+)' and 'Cl^(-)'. It is the 'H^(+)' ion that is the acid component and pH is measured against it.

HCl does NOT remain undissociated in water.

Yes I agree it can be confusing. The formula HCl is the same for the gas and the acid.