Communication.
When people exchange ideas about science, they are communicating with one another to both share and obtain knowledge. Collaboration is a large part of this communication, as the exchange of these ideas often leads to new discoveries and inventions.
This is a single replacement reaction. So the final products are a metal and a salt with replaced cation. In this case, the final products are copper (metal) and iron sulfate (salt).
The decay of a radioactive isotope can be predicted using the formula: A = Ao[2^(-t/T_0.5)] where A is the amount after time t, Ao is the original amount and T_0.5 is the half-life. Using the equation and the given values, 0.888 g of the sample will remain after 72 minutes.
You would use the formula for Boyle's Law:
(P1) (V1) = (P2) (V2)
(101.5) (2.0) = (P2?) (.75)
*P2 = 270kPa (You're allowed 2 significant figures)
P = Pressure
V = Volume