Ammonium iodide, or NH₄I, is a salt. Since all salts are strong electrolytes, when ammonium iodide is dissolved in water, it would dissociate into ammonium ions and iodide ions. Hence, the major species present would be: <em>NH₄⁺ and I⁻ ions</em>.
Answer:- 23.0 mg
Solution:- Radioactive decay obeys first order kinetics and the first order kinetics equation is:

where,
is the initial amount of radioactive substance and N is it's amount after time t. k is the decay constant.
From given information, Original amount,
of the radioactive substance is 184 mg and we are asked to calculate the amount N after 15 days. It means, t = 15 days
Half life is given as 5 days. From the half life, we could calculate the decay constant k using the equation:

where,
is the symbol for half life. let's plug in the value of half like to calculate k:


Let's plug in the values in the first order kinetics equation and solve it for N:


lnN = 3.136

N = 23.0 mg
So, 23.0 mg of Bi-210 would be remaining after 15 days.
Answer:
T₂ = 19.95°C
Explanation:
From the law of conservation of energy:

where,
mc = mass of copper = 37.2 g
Cc = specific heat of copper = 0.385 J/g.°C
mw = mass of water = 188 g
Cw = specific heat of water = 4.184 J/g.°C
ΔTc = Change in temperature of copper = 99.8°C - T₂
ΔTw = Change in temperature of water = T₂ - 18.5°C
T₂ = Final Temperature at Equilibrium = ?
Therefore,

<u>T₂ = 19.95°C</u>