Q = M * C *ΔT
Q / <span>ΔT = M
</span>Δf - Δi = 98.4ºC - 62.2ºC = 36.2ºC
<span>
C = 1137 J / 140 * 36.2
C = 1137 / 5068
C = 0.224 J/gºC</span>
Answer: Aufbau principle
Explanation: Aufbau Principle suggests that in filling electrons into orbitals, lower energy orbitals must be filled before higher energy orbitals.

28%
Explanation:
mass of solute(KBr) = 3.73g
mass of solvent(H2O) = 131g
mass of solution = mass of solute + mass of solvent
= 3.73 + 131
= 134.73g

We can use two equations for this problem.<span>
t1/2 = ln
2 / λ = 0.693 / λ
Where t1/2 is the half-life of the element and λ is
decay constant.
20 days = 0.693 / λ
λ = 0.693 / 20 days
(1)
Nt = Nο eΛ(-λt) (2)
Where Nt is atoms at t time, No is the initial amount of substance, λ is decay constant and t is the time
taken.
t = 40 days</span>
<span>No = 200 g
From (1) and (2),
Nt = 200 g eΛ(-(0.693 / 20 days) 40 days)
<span>Nt = 50.01 g</span></span><span>
</span>Hence, 50.01 grams of isotope will remain after 40 days.
<span>
</span>