Question

select all the mixtures. nickel water vapor smoke mercury

Explanation:

A mixture is a combination of two or more substances that are not chemically combined. Nickel is an element, water - vapor is a pure substance (water in gaseous state), and mercury is an element. Smoke is a mixture of solid particles (ash, etc.) and gases (such as carbon - dioxide, carbon - monoxide) released during combustion.

Answer:

Smoke