Moles of oxygen = mass/molar mass of O2 = 8/31.998 = 0.25 moles.
Number of particles = moles x 6.02 x 10^23 = 0.25 x 6.02 x 10^23 = 1.505 x 10^23 particles.
Hope this helps!
Taking the compound with the metallic counterpart of highest mass would be the answer. Looking at the periodic table, it is easy to realize that K has the highest mass out of H, Li, K, and Cl. Therefore, the answer is (2) KCl.
<span>[Ne] 3s2 3p5
Hope this helps!</span>
Answer:
independent variable - the thing you change
dependent variable - the thing you measure
control variables - the things you keep the same
The half life of 131 i is 8.06 days
calculation
by use of concentration time equation for radioactive decay
In Nt/No = -Kt
where Nt/No is the fraction of the sample remaining at time T
convert 50.2% in decimal = 50.2/100 = 0.502
therefore = In 0.502 = - K 8.0 t
- 0.689 =-8.0 k
divide both side by 8.0
K = 0.860
t1/2 = 0.693/K
t1/2 = 0.693/0.860 = 8.06 days