In this case, if we want to draw the <u>isomers</u>, we have to check the<u> formula </u> in this formula we can start with a linear structure with 4 carbons. We also know that we have a double bond, so we can put this double bond between carbons 1 and 2 and we will obtain <u>But-1-ene.</u>
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For the next isomer, we can move the double bond to carbons 2 and 3. When we do this can have two structures. When the methyl groups are placed on the same side we will obtain <u>Z-But-2-ene</u>. When the methyls groups are placed on opposite sides we will obtain <u>E-But-2-ene.</u>
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Finally, we can use a linear structure of three carbons with a methyl group in the middle with a double bond, and we will obtain <u>2-Methylpropene.</u>
I think the one that cause the equilibrium to shift would be : 3. adding a noble gas Adding the noble gas will add more concentration to the KNO3, which will create different amount of equilibrium