Dehydrohalogenation means removal of 1 H and 1 X group .When H and X are removed from a haloalkane it will lead to the formation of Alkene .

The reaction/method that does not give an alkane is Dehydrohalogenation of an alkyl halide.

Dehydrohalogenation refers to the removal of a hydrogen halide (such as HCl or HBr) from an alkyl halide, resulting in the formation of an alkene. This reaction is typically carried out using a strong base, such as sodium or potassium hydroxide. The strong base abstracts the hydrogen atom from the alkyl halide, leading to the elimination of a halide ion and the formation of a carbon-carbon double bond.

However, it is important to note that dehydrohalogenation does not result in the formation of an alkane. Alkanes are saturated hydrocarbons that contain only single bonds, while alkenes are unsaturated hydrocarbons that contain at least one carbon-carbon double bond. The removal of a hydrogen halide from an alkyl halide does not result in the addition of new hydrogen atoms to form a saturated hydrocarbon.

Explanation:

Catalytic hydrogenation of alkenes: In this reaction, alkenes are treated with hydrogen gas in the presence of a metal catalyst (such as platinum, palladium, or nickel) to form alkanes. The double bond in the alkene is broken, and two hydrogen atoms are added across the double bond, resulting in the formation of a saturated hydrocarbon (alkane).

Wurtz reaction: The Wurtz reaction is a coupling reaction in which two alkyl halides are reacted with sodium metal in dry ether to form a higher molecular weight alkane. This reaction involves the formation of a carbon-carbon bond by the combination of two alkyl radicals, resulting in the formation of an alkane.

Hydrolysis of alkylmagnesium bromide: Alkylmagnesium bromides, also known as Grignard reagents, react with water to form alcohols. The alkyl group is transferred from the magnesium to the oxygen atom in water, resulting in the formation of an alcohol. This reaction does not involve the formation of an alkane.

Dehydrohalogenation of an alkyl halide: As mentioned earlier, dehydrohalogenation involves the removal of a hydrogen halide from an alkyl halide, leading to the formation of an alkene. This reaction does not result in the formation of an alkane.

Therefore, among the given options, dehydrohalogenation of an alkyl halide is the reaction/method that does not give an alkane.