Yes Chloe is alive. Lex had kept her protected so she could testify against Lionel. The explosion made it look like she'd been killed thus, taking the heat off them. In reality there had been a tunnel under the hous & blah blah. It was a rich mans witness proctection plan. They did a good job to cause in the first episode Alison Mack's name wsn't in the credits, so everyone thought her character was killed off. Last night Alison's name was back in the permanent cast mix so YAY 4 her.