Statement I: 2-Bromobutane, on reaction with sodium ethoxide in ethanol gives 1-butene as a major product

Statement II: 1-Butene is less stable than 2-butene.

Statement I is false but statement II is correct

The answer is 4. Statement I is false but statement II is correct.

Statement I is false because 2-bromobutane, on reaction with sodium ethoxide in ethanol gives 2-butene as a major product. This is because the reaction proceeds through an S_N2 mechanism, which is a concerted reaction that takes place in a single step. In an S_N2 reaction, the nucleophile attacks the carbon atom from the back side, resulting in the inversion of the stereochemistry at the carbon atom. However, the product of the reaction is 2-butene, which is less stable than 1-butene. This is because 2-butene has a less symmetrical structure, which makes it more susceptible to steric hindrance.

Statement II is correct because 1-butene is more stable than 2-butene. The stability of an alkene is determined by the number of substituents on the carbon atoms of the double bond. The more substituents on the carbon atoms of the double bond, the more stable the alkene. In the case of 1-butene and 2-butene, 1-butene has two substituents on the carbon atoms of the double bond, while 2-butene has only one substituent. This makes 1-butene more stable than 2-butene.

Therefore, statement I is false but statement II is correct.