What is the net force on the box shown below?

picture attached!

The correct answer is 10 N to the left.

Let us recall that when two vectors acts in the same direction, the resultant vector is obtained by adding the two vectors.

Similarly, when vectors act in opposite direction, the resultant vector is obtained by subtracting the vectors.

The resultant of the all the vectors shown in the diagram is obtained by adding the two vectors shown on the right and subtracting the result from the magnitude of the vector shown on the left as follows;

Resultant vector = 60 N - (30 N + 20 N)

Resultant vector = 60 N - 50 N

Resultant vector = 10 N

The direction of this resultant vector is towards the left.

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answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a