Can can someone lease check my answers and tell me if im you have four fixed-volume containers at stp. container a has 0.5 mol of gas in 11.2 l. container b has 2 mol of gas in 22.4 l. container c has 1 mol of gas in 22.4 l. container d has 2 mol of gas in 11.2 l. which of the four containers have equal pressures? (points : 3) a and c a and b b and c c and d my answer is a

Technically, this question is badly worded. If all 4 containers were at STP, then all 4 containers would have the same pressure. So I'll assume instead that all 4 containers are at the same temperature, and then use the ideal gas law to determine the relative internal pressures of each container.

   The idea gas law is
  PV = nRT
  where
  P = Pressure
 V = Volume
  n = number of moles
 R = Ideal gas constant
 T = Absolute temperature

    Since all the containers are at the same temperature, we can ignore the R and T parts of the formula and substitute some value K for constant. So we get PV = nK

   Now solve for P
 PV = nK
 P = nK/V

   From the above, you can see that the pressure is proportional to the number of moles divided by the volume. So let's calculate that value for each container.
 Container A: 0.5 / 11.2 = 0.044642857
 Container B: 2 / 22.4 = 0.089285714
Container C: 1 / 22.4 = 0.044642857
Container D: 2 / 11.2 = 0.178571429
   So as you can see, the pressures in containers A and C are the same, which is the first available option, so you are correct.

Aquantity of that isotope to decay to 1/2 of  its original value

Well you can immediately rule out a and d because if a metal were to lose or gain protons, then it would become a different element all together. the answer here is b because the positive symbol with a number refers to how many electrons the metal can give away to become stable.