The correct answer is C: A radiation consisting of uncharged particles is emitted when alpha particles strike beryllium atoms.
Explanation:
Chadwick discovered neutron while experimenting with a gold foil. A stream of alpha particles produced from a polonium source was directed at beryllium target. It was noticed that some penetrating radiations were produced. These uncharged particles were called neutrons because on the charge detector these particles showed no deflection.
Their nuclear reaction is as follow.
₂He + ₄Be ----------> ₀n + ₆C
Chadwick noticed that neutrons cannot ionize gases and are highly penetrating particles.
In this case, since the density in the international system of units is given in terms of kg for the mass and L for the volume, we need to perform a process of units conversions from mg and dL to kg and L as show below: