The second most abundant element found in the universe is:

Explanation:

• Hydrogen: It is denoted by the symbol H and found in the form of its isotope protium (₁H¹), deuterium(₁H²), tritium (₁H³). 
  • ​It is Created during the hot Big Bang but depleted by stellar fusion, ~70% of the Universe remains hydrogen.
• Helium: It is denoted by He (₂He⁴). It is formed by the fusion reaction of hydrogen in stars.
  •  About 28% is helium, with 25% formed in the Big Bang and 3% from stellar fusion.
• Oxygen: It is denoted by O (₈O¹⁶).
  • The most common (~1%) heavy element, oxygen arises from fusion in massive, pre-supernova stars.
• Carbon: It is denoted by C (₆C¹²).
  • The first heavy element created by stars, carbon mostly originates within red giants.

So, Helium is the second most abundant element found in the universe.