10 points How may the formation of a gas indicate that a chemical reaction has occurred?

Formation of a gas or precipitate indicates that an irreversible reaction has occurred

Formation of a gas indicates that a physical reaction has occurred

Gases are given off every time a chemical reaction occurs

Formation of a gas is a physical property of all chemical reactions

Item at position 4
4

Gases are given off every time a chemical reaction occurs

Explanation:

Formation of a new gas

Formation of a precipitate

A new smell is given off

Heat is released

Explanation: A chemical reaction exhibits the following characteristics: formation of new substance, heat emission is an exothermic process which is due to chemical reactions

Precipitate formation occurs when insoluble substances are formed in an ionic compound solution.

And smells or odor are caused by the production of new substances.

lunar landing mission. apollo 11 was the first manned mission to land on the moon. the first steps by humans on another planetary body were taken by neil armstrong and buzz aldrin on july 20, 1969. the astronauts also returned to earth the first samples from another planetary body.

explanation:

the correct answer is b