The number of alkene isomers with the molecular formula $C_4H_8$ is ....

Which of the following alkenes does not undergo anti-Markovnikov addition of $HBr$?

What is the product formed when $trans-2$-butene reacts with $D_2$ in the presence of a $Ni$ catalyst?

$2-$hexene $\xrightarrow[(i) O_3]{(ii) H_2O}$ Products
The two products formed in the above reaction are -

In the absence of peroxide,what is the first step in the addition of $HBr$ to propene?

Assertion : $1$-Butene on reaction with $HBr$ in the presence of a peroxide produces $1$-bromobutane.
Reason : It involves the formation of a primary radical.