Final answer:
Confirm the presence of carbon in a compound, Lassaigne's test is used. Beilstein's test is for detecting halogens. When analyzing carbon atoms with a mass number greater than 12, it indicates the presence of carbon isotopes.
Step-by-step explanation:
The test that can be used to confirm the presence of carbon in a compound is Lassaigne's test (Option A). Lassaigne's test is a qualitative analysis procedure used to detect elements such as nitrogen, sulfur, and halogens in organic compounds.
However, Beilstein's test (Option B) is specifically used for detecting the presence of halogens in the sample. When you analyze a sample of carbon and determine that 6% of the carbon atoms in your sample have a mass number greater than 12, it would mean that 6% of the sample is comprised of carbon isotopes, as the most common isotope of carbon has an atomic mass of 12.
In the context of detecting the presence of a specific virus, tests such as EIA, RT-PCR, and PCR (Option D) can all be used to detect the presence of a virus, as they are techniques used to identify viral antigens or genetic material associated with the virus.