Question

What element spontaneously splits into a lighter nucleus and an even lighter helium nucleus?1) boron2) carbon3) radium4) tungsten

Answer 1

3) radium

Step-by-step explanation

For an element to spontaneously split into a lighter nucleus (and an even lighter helium nucleus), the element must be a radioactive element.

From the options, the only naturally radioactive element is radium which splits (decays radioactively) as follows:

`Ra\to X+\alpha`

where X = lighter nucleus, α = helium nucleus.

Therefore, the answer is option 3.