Ketones react with Mg - Hg over water gives : - Tardigrade
Solution: Ketones on reduction with magnesium amalgum and water form pinacols. Ketones upon reaction with Grignard regent from tertiary-alcohol. Formaldehyde with Grignard reagent forms primary alcohol, acetaldehyde with Grignard reagent forms secondary alcohol. 2∘ alcohol (except formaldehyde which form 1∘ alcohol).