In arc welding eyes need to be protected against?

Hint: An electric arc is a visible plasma discharge which is between the two electrodes that is resulted from the electrical current ionizing gases in the air. Electric arc welding is a process of welding in which an electric arc is used to provide heat to melt and join metals.

Complete answer:
We know that an electrical arc is an electrical current which can be either unintentionally or intentionally discharging itself via a gas, vapour, or air across a gap between two electrodes and expending relatively a lower voltage across the conductors.
In this process, a power supply is introduced between the electric arc (which can be consumable or non-consumable) and a base material by using either direct current (DC) or alternating (AC) current.
We know that the metals easily chemically react to oxygen and nitrogen present in the air when they are heated to high temperatures by the electric arc, slag or protective shielding gas is introduced to reduce the contact of the molten metal with the air. Hence, after cooling, the molten metal solidifies and form a metallurgical bond
Therefore, in arc welding eyes need to be protected from the small chips of metals and the harmful radiation emitted such as UV or IR radiations.

Note:
The advantages of arc welding are that it has a high speed and efficiency. It needs simple apparatus. It can form a powerful bond between the metals. Some of the disadvantages of arc welding are that an expert operator is needed to operate the machinery and this process is not clean for reactive metals like aluminium and titanium.