Answer:<span>d. 145 minutes
</span>
Half-life is the time needed for a radioactive to decay half of its weight. The formula to find the half-life would be:
Nt= N0 (1/2)^ t/h
Nt= the final mass
N0= the initial mass
t= time passed
h= half-life
If 25.0% of the compound decomposes that means the final mass would be 75% of initial mass. Then the half-live for the compound would be:
Nt= N0 (1/2)^ t/h
75%= 100% * (1/2)^ (60min/h)
3/4= 1/2^(60min/h)
log2 3/4 = log2 1/2^(60min/h)
0.41503749928 = -60min/h
h= -60 min / 0.41503749928= 144.6min
To find the concentration of hydronium ions, take 10 raised to the negative pH:
10^-9.56= 2.75 x10^-10M
To find the concentration of hydroxide ions, take 10 raised to the negative pOH: 10^-4.44 = 3.63 x10^-5M
The answers would be the mass before a reaction is the same as the mass after a reaction which basically means mass is conserved
Answer:
control.
Explanation:
during an experiment you are required to maintain a separate group of subjects to collect data on so you will be able to make comparisons from your observations. assuming the watered plants grew, what does that mean? they grew at a quicker rate? slower rate? the same rate? compared to what? you need this control group in order to prove your observations either one way or the other such as "compared to unwatered plants, the watered plants grew at *blank* rate."
