Question: Read this and answer the question

Apart from its use as a reactant, H
2 has wide applications in physics and engineering. It is used as a shielding gas in welding methods such as atomic hydrogen welding. H2 is used as the rotor coolant in electrical generators at power stations, because it has the highest thermal conductivity of any gas. Liquid H2 is used in cryogenic research, including superconductivity studies. Because H
2 is lighter than air, having a little more than 1⁄14 of the density of air, it was once widely used as a lifting gas in balloons and airships.

Why is it used as the rotor coolant?
Answer: it has the highest thermal conductivity of any gas
Question: Read this and answer the question

Zapatist forces, which were based in neighboring Morelos had strengths in the southern edge of the Federal District, which included Xochimilco, Tlalpan, Tláhuac and Milpa Alta to fight against the regimes of Victoriano Huerta and Venustiano Carranza. After the assassination of Carranza and a short mandate by Adolfo de la Huerta, Álvaro Obregón took power. After willing to be re-elected, he was killed by José de León Toral, a devout Catholic, in a restaurant near La Bombilla Park in San Ángel in 1928. Plutarco Elias Calles replaced Obregón and culminated the Mexican Revolution.

Who was the third to last leader before the end of the Mexican Revolution?
Answer: Adolfo de la Huerta
Question: Read this and answer the question

The 132nd Street Community Garden is located on 132nd Street between Adam Clayton Powell Jr. Boulevard and Malcolm X Boulevard. In 1997, the lot received a garden makeover; the Borough President's office funded the installation of a $100,000 water distribution system that keeps the wide variety of trees green. The garden also holds a goldfish pond and several benches. The spirit of the neighborhood lives in gardens like this one, planted and tended by local residents.

How much did the 132nd Street Community Garden's water distribution system cost?
Answer:
$100,000