What is the half-life of a radioisotope if a 20 g sample becomes 5 g after 2 days?

If 10.g of agno3 is available, what volume of 0.25 m agno3 can be prepared

3.) for each of the following compounds, draw the major organic product of reaction with hcl or naoh and circle whether the starting materials and products will be more soluble in organic solvent or water benzoic acid + hcl: benzoic acid + naoh: oh benzoic acid water/organic water organic fluorenone hс: fluorenone + naoh: fluorenone water/organic water/organic веnzocaine + hci: benzocaine + n»oh: h2n benzocaine water/organic water organic o=

Can someone me with questions 15 to 17 plz.