Determine if the following arguments are valid or invalid. Explain your answer in one or two sentences.
1. No gemstones that do not contain chromium are emeralds. Therefore, some stone that are not emeralds are not gemstones that contain chromium.
2. It is false that no unhealthy things to ingest are food additives. Therefore, some food additives are not healthy things to digest.
3. Some people who recognize paranormal activity are not non-scientists. Therefore, it is false that no scientists are people who recognize paranormal activity.
4. It is false that some feminists are not advocates of equal pay for equal work. Therefore, it is false that all advocates of equal pay for equal work are non-feminists.
5. Some pleasant recollections are not missed opportunities. Therefore, some availed opportunities are not unpleasant recollections.