Which product is present in the electrolysis of all the following electrolytes: concentrated hydrochloric acid, concentrated aqueous sodium chloride and dilute sulfuric acid?

The product present in the electrolysis of all the mentioned electrolytes (concentrated hydrochloric acid, concentrated aqueous sodium chloride, and dilute sulfuric acid) is Hydrogen gas (H2).

Here's the step-by-step explanation:

1. Electrolysis of concentrated hydrochloric acid: When concentrated hydrochloric acid (HCl) is electrolyzed, it dissociates into hydrogen ions (H+) and chloride ions (Cl-). The hydrogen ions gain electrons at the cathode to form hydrogen gas (H2), and the chloride ions lose electrons at the anode to form chlorine gas (Cl2).

2. Electrolysis of concentrated aqueous sodium chloride: In this case, sodium chloride (NaCl) dissociates into sodium ions (Na+) and chloride ions (Cl-). Water also dissociates into hydrogen ions (H+) and hydroxide ions (OH-). At the cathode, hydrogen ions gain electrons to form hydrogen gas (H2), and at the anode, chloride ions lose electrons to form chlorine gas (Cl2).

3. Electrolysis of dilute sulfuric acid: When dilute sulfuric acid (H2SO4) is electrolyzed, it dissociates into hydrogen ions (H+) and sulfate ions (SO4 2-). The hydrogen ions gain electrons at the cathode to form hydrogen gas (H2), and at the anode, water is oxidized to form oxygen gas (O2) and hydrogen ions.

So, in all three cases, hydrogen gas is produced at the cathode during electrolysis.