Question

reactivity series of metals
lithium
rubidium
potassium
barium
calcium
sodium
magnesium
aluminum
manganese
zinc
chromium
iron
cobalt
nickel
tin
lead
hydrogen
copper
silver
mercury
platinum
gold

options:
aluminum
calcium
copper
nickel

Explanation:

To solve this, we analyze the reactivity series:

• Aluminum, Calcium, Nickel are above Hydrogen (more reactive), while Copper is below Hydrogen (less reactive). If the question is about the least reactive among the options (or related to reactivity below H), we check positions.

Looking at the series: Calcium > Aluminum > Nickel > Copper (since Copper is below Hydrogen, and the others are above). So if the question is about the metal with lower reactivity (e.g., least reactive in options), Copper is the answer.

The reactivity series shows metals' reactivity order. Among Aluminum, Calcium, Copper, Nickel, Copper is below Hydrogen (less reactive) while the others are above. So if the question relates to lower reactivity, Copper is the choice.

Answer:

Copper