Which one is an unsaturated compound?

Ethylene reacts with $Br_2$ to give $1, 2$-dibromoethane. Which intermediate is formed that leads to anti-addition?

The reaction $R-CH=CH_2 \xrightarrow{Na/NH_3, C_2H_5OH} R-CH_2CH_3$ is known as:

What is the product formed when ethylene reacts with $1\%$ cold alkaline $KMnO_4$?

Among the alkenes,which one produces tertiary butyl alcohol on acid hydration?

The number of grams of bromine that will completely react with $5.0 \ g$ of pent$-1-$ene is $...... \times 10^{-2} \ g$. (Atomic mass of $Br = 80 \ g/mol$) [Nearest Integer]