Answer:
D. A brown gas produced
Explanation:
When a chemical reaction occur, there are several changes that takes place such as change in color, odor change, formation of a gas, and formation of a precipitate etcetera.
In the given chemical reaction, two colorless gas (NO and O2) react together and form brown gas (NO2). So, the change of gas from colorless to brown gas is the evidence that shows chemical reaction occurred.
Hence, the correct option is "D. A brown gas produced".
I think it is called mechanical digestion. Or alas, chemical digestion. One of those. Or both!
Hope helps-aparri
(thank yous are welcome)
<span>There are many indicators for predator presence. Some of them are:
Being able to spot predator marks like scratches or fur.
Being able to feel predator movements.
</span><span>Echo-location </span>For example, moths respond to the echo-location calls from their bat predators; moths drop to the ground once they hear the sound pulse from the bat.
