Carbon dioxide is a pure substance. A pure substance can be an element or a compound. Carbon dioxide is a pure compound, consisting of two kinds of atoms that are bonded together. An element consists of merely one kind of atom. For example, oxygen is an element.
For Downâs syndrome, a blood test called the quadruple test is available from weeks 14-20 of pregnancy. For Patauâs and Edwardsâ syndromes, you will be offered a mid-pregnancy scan that checks for physical abnormalities.
With Down syndrome, the extra chromosome causes delays in the way a child develops, mentally and physically. The physical features and medical problems associated with Down syndrome can vary widely from child to child. While some kids with DS need a lot of medical attention, others lead healthy lives.