Titan is the moon of Saturn recently explored by Cassini-Huygens mission. What gas is the predominant component of Titan’s atmosphere(over 98 percent)?

Titan's atmosphere is composed primarily of nitrogen, making up over 98% of its atmospheric composition. This is similar to Earth's atmosphere, which is about 78% nitrogen. Methane is also present on Titan (about 1-2%), but it's a trace gas compared to nitrogen. Oxygen and hydrogen are not major atmospheric components on Titan - oxygen is bound in water ice, while hydrogen is too light to be retained in significant quantities.