Question

lesson 42 - classification of materials
how does the team know the gas produced is hydrogen?
(1 point)
flame test
temperature
density
direct observation

Explanation:

Hydrogen gas burns with a characteristic "pop" sound when ignited in a flame test. This is a common method to identify hydrogen. Temperature and density are not specific enough to uniquely identify hydrogen. Direct observation is not feasible as hydrogen is a colorless and odorless gas.

Answer:

flame test