Q: What is the most abundant element in the universe?


Read this paragraph and choose the correct option from the provided answers:

Isotopes of Hydrogen Hydrogen, the most abundant element in the universe, is the ultimate source of all other elements by the process of nuclear fusion. (For more information on nuclear fusion, seeChapter 20 "Nuclear Chemistry". ) Table 21.2 "The Isotopes of Hydrogen" compares the three isotopes of hydrogen, all of which contain one proton and one electron per atom. The most common isotope is protium (1H or H), followed by deuterium (2H or D), which has an additional neutron. The rarest isotope of hydrogen is tritium (3H or T), which is produced in the upper atmosphere by a nuclear reaction when cosmic rays strike nitrogen and other atoms; it is then washed into the oceans by rainfall. Tritium is radioactive, decaying to 3He with a half-life of only 12.32 years. Consequently, the atmosphere and oceans contain only a very low, steadystate level of tritium. The termhydrogen and the symbol H normally refer to the naturally occurring mixture of the three isotopes. Table 21.2 The Isotopes of Hydrogen.

 Choices:

- carbon

- helium

- nitrogen

- hydrogen


A:
hydrogen