Is it true that air is an opaque material?

The above statement is false.
If no light is able to pass through an object, it is known as an opaque material. For example, butter paper, frosted glass, muddy water, etc. On the other side, materials like air, water, and clear glass are known as transparent. When the light comes across transparent materials, almost all of it passes directly through them. And the air is transparent to all visible light.
The corrected statement would be, “Air is a transparent material”.