Which observation describes potassium reacting with water?

Which observation describes potassium reacting with water?

• A. Fizzing
• B. Lilac flame
• C. Potassium disappears
• D. Floats

Answer: (B)

When potassium meets water, it reacts vigorously to form potassium hydroxide and hydrogen gas. The key observable is fizzing—bubbles of hydrogen escaping from the surface indicate the chemical reaction taking place. The lilac flame describes potassium burning in a flame, which is a separate situation rather than the reaction with water itself. So the fizzing from hydrogen gas is the most direct description of potassium reacting with water.

When potassium meets water, it reacts vigorously to form potassium hydroxide and hydrogen gas. The key observable is fizzing—bubbles of hydrogen escaping from the surface indicate the chemical reaction taking place. The lilac flame describes potassium burning in a flame, which is a separate situation rather than the reaction with water itself. So the fizzing from hydrogen gas is the most direct description of potassium reacting with water.