Answer:
Most radioactive materials decay and they mostly have a decay rate. The time it takes for half of a radioactive material to decay is called half life.
The 7 minute significance of half-life simply points to the total time it takes after which half of the radioactive material would have completely decayed,
Answer is: pH of methylamine is 12,2.
Chemical reaction: CH₃NH₂(aq)+ H₂O(l) ⇌ CH₃NH₃⁺(aq) + OH⁻<span>(aq).
Kb(</span>CH₃NH₂) = 4,4·10⁻⁴.
c₀(CH₃NH₂) =
0,57 M.
c(CH₃NH₃⁺) = c(OH⁻) =
x.
c(NH₂OH) = 0,57 M - x.
Kb
= c(CH₃NH₃⁺) · c(OH⁻) / c(CH₃NH₂).
0,00044 = x² / (0,57 M - x).
Solve
quadratic equation: x = c(OH⁻) =
0,0156 mol/L.
pOH
= -log(0,0156 mol/L.) = 1,80.
pH
= 14 - 1,80 = 12,2.
25 g of NH₃ will produce 47.8 g of (NH₄)₂S
<u>Explanation:</u>
2 NH₃ + H₂S ----> (NH₄)₂S
Molecular weight of NH₃ = 17 g/mol
Molecular weight of (NH₄)₂S = 68 g/mol
According to the balanced reaction:
2 X 17 g of NH₃ produces 68 g of (NH₄)₂S
1 g of NH₃ will produce 
g of (NH₄)₂S
25g of NH₃ will produce 
of (NH₄)₂S
= 47.8 g of (NH₄)₂S
Therefore, 25 g of NH₃ will produce 47.8 g of (NH₄)₂S
Assume positive charges
directions outwards from source points like field lines of two repelling magnets
Percentage
by mass is the amount in mass of a component in a mixture per 100 unit of mass of the total
mixture. Percentage by mass is the same as %w/w. In order to determine this value, we need to know the mass of the substance in question and the total mass of the sample. In this case, we have to know the mass of Fe by doing certain calculations. Then, we divide this value by the total mass given of the ore, 4.05 g and multiply by 100%. It should be expressed as follows:
Percent by mass = mass of Fe in ore / 4.05 g ore sample x 100
However, the question is lacking some information so we cannot really specify the answer.
