An unidentified, light-colored igneous rock is made up of potassium feldspar and quartz. to what family of igneous rocks does the rock belong?

Felsic - Felsic igneous rocks, like granite. They are rich is feldspar, silica and quartz, and are light colored. In fact, the word 'felsic' was derived by comining the words Feldspar and Silica. Other examples of Felsic igneous rocks include  rhyolote, obsidian and pumice.