1. When propene is treated with HBr, both 2-bromopnopane and 1-bromopropane are formed as products. The major product is2- Bromo-propane. This is due to the rule known as Markonikos rule of addition. It states that when a hydrogen halide is added to an unsymmetrical alkene, the halogen atom will goes to the doubly bonded carbon containing lesser number of hydrogen atoms.
2. In Acetylene, the hybridisation of carbon is sp and hence 50% s-character is present.
