Why was the gemini program valuable to future space programs?

The Gemini program which took place from 1965 to 1966 was valuable to future space programs because the astronauts established a smooth way of landing, docking with other spaceships, as well as many flights into space allowed them to test the environment and its effect on astronauts.  It helped the astronauts to become better prepared for those effects and different conditions.

after balancing the chemical equation, what are the coefficients for these compounds?

h2s      

⇒ 3

hno3    

⇒ 2

works for edg

can you explain a little further maybe give multiple choice? ?