What is the definition of half-life?

12.00 moles of naclo3 will produce how many grams of o2? a) 256 g of o2 b) 576 g of o2 c) 288 g of o2

0.2348 grams of pbcl2 used to form 44.0 ml of solution.

Fill in the coefficients that will balance the following reaction: a0cr2(so4)3 + a1agno3 -> a2cr(no3)3 + a3ag2so4