most abundant element in the universe

So, which is the most abundant element in the universe?
Hydrogen is the most abundant element in the known Universe; helium is second.

Helium makes up most of the remaining 25%. Oxygen is the third most abundant element in the universe. All of the other elements are relatively rare.Silicon is the seventh most abundant element in the universe and the second most abundant element in the earth’s crust.

universal blood type

Type O blood is the universal blood type and is the only blood type that can be transfused to patients with other blood types.

Patients who have type AB blood are considered universal recipients because they can receive blood or blood products from any other blood type. However, these patients may only donate their blood to patients who have AB blood.
Type O blood (called type zero in some countries) has neither the A or B antigen and therefore, type O negative blood can be given to anyone. Persons with type O negative blood are referred to as “universal donors”.