1 is Uebelmannia pectinifera, a species rather prized by growers - not one you see often in box stores
2 is a Mammillaria
3 ?
4 is Cleistocactus winteri ssp. winteri (aka Borzicactus aurespinus, Hildewinteria aurespina if you're googling these to check)
5 ?
6 ?
7 is a grafted plant (on Hylocereus undatus) of perhaps some sort of Echinopsis?? that has no chlorophyll so can't survive unless grafted on something green. These tend not to live for very long
8 is Parodia haselbergii ssp. graessneri (aka Notocactus graessneri)
9 is Opuntia monacantha, the variegated and monstrose form.
2, 3 and 9 particularly are showing misshapen growth due to lack of light. Try to find the sunniest windowsill you can (though in Summer a week in semi sun might be needed so that they don't burn while they're getting used to brighter light).
