Just remember how many electrons can each sublevel hold.
S=2
P=6
D=10
Since we have 10 for atomic number, we can assume we have 10 electrons
1S2
2S2
2P6
The rest have zero because we already have 10 (2+2+6=10)
Answer: a) The concentration after 8.8min is 0.17 M
b) Time taken for the concentration of cyclopropane to decrease from 0.25M to 0.15M is 687 seconds.
Explanation:
Expression for rate law for first order kinetics is given by:

where,
k = rate constant
t = age of sample
a = let initial amount of the reactant
a - x = amount left after decay process
a) concentration after 8.8 min:



b) for concentration to decrease from 0.25M to 0.15M


Salt makes the freezing point of water decrease, so it would freeze at a warmer temperature than regular water
So potassium is more reactive than lithium because the outer electron of a potassium atom is further from its nucleus than the outer electron of a lithium atom. Hope this answers the question. Have a nice day. Feel free to ask more questions.