How do you know if a reaction is endothermic? 40 !

Atank contains 240 liters of fluid in which 10 grams of salt is dissolved. brine containing 1 gram of salt per liter is then pumped into the tank at a rate of 6 l/min; the well-mixed solution is pumped out at the same rate. find the number a(t) of grams of salt in the tank at time t.

Ibeg i need 20. a reaction produces 4.93 l of oxygen, but was supposed to produce 1 mol of oxygen. what is the percent yield?

Name the element in group 17, period 2. (periodic table)