Number of isomeric alcohols of molecular formula C₆H₁₄O which give positive iodoform test is

On hydrolysis of a ''compound'', two compounds are obtained. One of which one treatment with sodium nitrite and hydrochloric acid gives a product which does not respond to iodoform test. The second one reduces Tollens reagent and Fehling's solution. The ''compound'' is

Some reactions of amines are given. Which one is not correct?

In DNA, the linkages between different nitrogenous bases are