These are three organic chemistry questions

regarding stability. Can you please help explain why a primary carbocation is less stable than a tertiary, why BH3 THF is a better reagent than NaBH4, and how the products of hydroboration/oxidation reactions differ in stability by whether it is an alkene or alkyne?

The stability of radicals and carbocations follow the same trend . With this rational in mind , explainWhy a primary carbocation formed during the electrophilic addition of H – Br to an alkene is less stablethan the corresponding tertiary carbocation5 ) Explain why BH 3 – THE is an excellent reagent for the hydroboration of alkenes , whileile NaBHA does notreact in a similar fashionIn the hydroboration / oxidation of alkenes , the final product results in the formation of the anMarkovnikov alcohol . However , when this same reaction is conducted with allynes , the product thatis formed is the ketone or aldehyde . Explain this observation in terms of energetics and stability