Answer : The partial pressure of 
is, 222.93 torr
Explanation :
Half-life = 2.81 hr = 168.6 min
First we have to calculate the rate constant, we use the formula :
Now we have to calculate the partial pressure of
The balanced chemical reaction is:
Initial pressure 760 0 0
At eqm. (760-2x) 4x x
Expression for rate law for first order kinetics is given by:
where,
k = rate constant
t = time passed by the sample = 215 min
a = initial pressure of 
= 760 torr
a - x = pressure of at equilibrium = (760-2x) torr
Now put all the given values in above equation, we get:
The partial pressure of = x = 222.93 torr
I believe the answer is 100. Hope this helps. (ﾉ◕ヮ◕)ﾉ*:･ﾟ✧
density = mass/volume.
Energy is required to change the phase of a substance, such as the energy to break the bonds between molecules in a block of ice so it may melt.
During a phase change energy my be added or subtracted from a system, but the temperature will not change. The temperature will change only when the phase change has completed. No temperature change occurs from heat transfer if ice melts and becomes liquid water (i.e., during a phase change). For example, consider water dripping from icicles melting on a roof warmed by the Sun. Conversely, water freezes in an ice tray cooled by lower-temperature surroundings. Energy is required to melt a solid because the cohesive bonds between the molecules in the solid must be broken apart so that the molecules can move around at comparable kinetic energies; thus, there is no rise in temperature.
Answer:
isotopes, there elements with a diffrent type atomic weight then the original, usally due to a higher amout of neutrons than the original. Some Isotopes are just as useable as the normal versions, but in some cases, such as Uranium, they can be even more radioactive than the original form
