In ADHD, what word does the H stand for?

Adelheid Wette, Engelbert Humperdinck's sister, wrote the libretto for which 1893 opera about a fairy tale pair? In June 1942, Adeline Gray made the first jump with a parachute made of which material? Adenine, thymine, cytosine and guanine are the bases of which molecule? What does the Portuguese word "adeus" mean? Which word describes food that follows Jewish dietary law? Adidas products for which sport include cleats and the official ball of the 1998 World Cup? In 1908 Adina De Zavala barricaded herself inside which San Antonio landmark to save it? Which adjective can go before Britain, Dane and Gatsby?