What type of reaction does this diagram below represent?

Nuclear fusion

Explanation:

The reaction shown in the diagram depicts a nuclear fusion.

 The reaction expression is given as:

        ²₁H   +   ³₁H     →     ⁴₂He   +   ¹₀n  + energy

This reaction is a nuclear fusion expression. Here two small lighter nuclide to form a product with an attendant emission of a neutron and energy.

The combination of lighter nuclides to form a heavier one is nuclear fusion.

Fusion is different from nuclear fission in which a heavier nuclide splits up.

if you answer my question i will answer yours

float.

archimedes' principle

denser than water sinks in water.

denser than mercury would sink in it