Question

Distinguish b/w But-2-ene and But -3ene​

Answer 1

$\huge \fbox \pink { a} \fbox \green {n} \fbox \red {s} \fbox \blue {w} \fbox \orange { e} \fbox \purple { r}$

In alkenes and alkynes the longest chain is taken which contains all the multiple bonds so in butene, that contains 4 carbon atoms we have two choices and not four. We cannot have but-4-ene and but-3-ene as they are they are technically but-1-ene and but-2-ene respectively when flipped. So count from any side, for example left side and when u reach the second carbon atom,draw a double bond between the second and the next. You have successfully drawn but-2-ene. Now draw a double bond between first and second for but-1-ene. If the structure is given and u are confused na bro if it's 1 or 2 or 3 or whatever. Start counting from the side where double or triple bond is closer from and the number on which u reach the multiple bond will be the required number that is 1,2 or any other number. Hope u like the answer