Both HNO3 and CH3COOH can be classified as

• A. Arrhenius acids that turn blue litmus red
• B. Arrhenius bases that turn blue litmus red
• C. Arrhenius acids that turn red litmus blue
• D. Arrhenius bases that turn red litmus blue

Answer: (A)

Acids in the Arrhenius framework are substances that increase hydrogen ion concentration in water, giving the solution an acidic character that turns blue litmus paper red. Both nitric acid and acetic acid do that: when dissolved, they release H+ (hydronium ions) into the solution. Nitric acid dissociates fully, while acetic acid dissociates only partially, but each still provides H+ to the water, making the solution acidic. That acidic environment changes blue litmus to red. Bases, on the other hand, produce OH- and turn red litmus blue. So these compounds are Arrhenius acids and cause blue litmus paper to turn red.