Sodium salt of an organic acid ‘X’ produces effervescence with conc. H₂SO₄. ‘X’ reacts with the acidified aqueous CaCl₂ solution to give a white precipitate which decolourises acidic solution of KMnO₄. ‘X’ is :

The major product obtained in the following reaction is :

Which of the following, upon treatment with tert-BuONa followed by addition of bromine water, fails to decolorize the colour of bromine?

3-Methyl-pent-2-ene on reaction with HBr in presence of peroxide forms an addition product. The number of possible stereoisomers for the product is :