Oh yes absolutely op’s x chromosome is expressed. I just meant unlike all the other chromosomes where in general both gene copies on both chromosomes are expressed, in xx individuals usually one of the x chromomes is inactivated and only one of them is being expressed at a time. The x chromosome has many essential genes. This is why we have x linked genetic diseases as well. Often xx individuals are just carriers or more mildly affected since they have two x chromosomes, and xy individuals are more severely affected since they have no backup copies of that gene.