Question

Rita added dilute hydrochloric acid to four metals. She recorded her observations in the table given below. While noting her observations she made some errors.

	Metals	Observations
1	copper	a gas was given off
2	iron	a gas was given off
3	magnesium	no a gas was given off
4	zinc	a gas was given off

Which observation(s) made by Rita is/are correct?

पर्याय

• 1 only

• 3 only

• Both 1 and 4

• Both 2 and 4

Answer 1

Both 2 and 4

Explanation:

Dilute HCl reacts with metals that are more reactive than hydrogen to give a salt and hydrogen gas; iron and zinc do so, while copper does not.

For example: \[\ce{Fe + 2HCl → FeCl2 + H2↑}\]. The general rule that an active metal + dilute HCl → salt + hydrogen supports that Mg, Zn, and Fe evolve H₂ (so Mg would have given a gas too), whereas copper does not.