A solution that turns blue litmus red gives no gas with copper but gives gas with magnesium. What is the correct reason?
Answer and explanation
Correct answer: Magnesium is more reactive than copper
Blue litmus turning red establishes that the solution is acidic. An acid can liberate hydrogen only from a metal placed above hydrogen in the reactivity series. Magnesium is above hydrogen and reacts with dilute acids, producing hydrogen gas; copper is below hydrogen and normally cannot displace it from a non-oxidising dilute acid. Thus option A correctly explains both observations.
Frequently asked questions
What is the correct answer to this question?
Magnesium is more reactive than copper
Why is this the correct answer?
Blue litmus turning red establishes that the solution is acidic. An acid can liberate hydrogen only from a metal placed above hydrogen in the reactivity series. Magnesium is above hydrogen and reacts with dilute acids, producing hydrogen gas; copper is below hydrogen and normally cannot displace it from a non-oxidising dilute acid. Thus option A correctly explains both observations.
Which subject and chapter does this question cover?
This is a Class 10 Science question. Chapter: Chemical Substances – Nature and Behaviour. Topic: Acids, Bases, and Salts.
