Q. 1. What is the purpose of the "Chalice Veil?"

A. 1. During the Eucharist celebrations (the Holy Mass), the "Chalice Veil" is used to cover the Chalice and paten to keep dust and flying insects away from the host and wine that will be transformed into the Body and Blood of Christ. The Chalice Veil is often made of rich material. Not only does it have a practical purpose, but it is also intended to show honor to the vessels used for the Sacrament of the Holy Eucharist.

In the West, a single Chalice Veil is normally used. The Veil will usually be the same material and color as the priest's vestments, though it may also be white. It covers the Chalice and paten when not actually in use on the Altar.

In the East, three Veils are used: one for the Chalice, one for the diskos (paten), and a third one (the Aër) is used to cover both. The Veils for the Chalice and diskos are usually square with four lappets hanging down the sides, so that when the Veil is laid out flat it will be shaped like a cross. The Aër is rectangular and usually larger than the Chalice Veil used in the West. The Aër also figures prominently in other liturgical respects.

[Source: https://en.wikipedia.org/wiki/Veil]