Answer: Mg is the excess reactant for the forward reaction.
Explanation: It is a stoichiometry problem and solved with the help of given grams and using balanced equation. Grams of both the reactants are converted to moles and divided by their coefficients. The excess reactant is the one for which we get the highest number on doing above steps.
The balanced equation is:
Molar mass of silicon tetra chloride is 169.9 gram per mol and the molar mass of Mg is 24.3 gram per mol.
= 
= 2.67 mol Mg
From balanced equation, the coefficient of silicon tetra chloride is 1 and that of Mg is 2. So, we will divide the moles of silicon tetra chloride by 1 and that of Mg by 2 and see which one gives highest number.
For silicon tetra chloride, 
= 0.317
and for Mg, 
= 1.34
The highest number is for Mg and so the excess reactant for the forward reaction is Mg.
<h3>
Answer:</h3>
Initial temperature is 243.59°C
<h3>
Explanation:</h3>
The quantity of heat is calculated by multiplying the mass of a substance by its specific heat capacity and change in temperature.
That is; Q = m×c×ΔT
In this case;
Quantity of heat = 560 J
Mass of the Sample of Zinc = 10 g
Final temperature = 100°C
We are required to determine the initial temperature;
This can be done by replacing the known variables in the formula of finding quantity of heat,
Specific heat capacity, c, of Zinc = 0.39 J/g.°C
Therefore,
560 J = 10 g × 0.39 J/g°C × ΔT
ΔT = 560 J ÷ (3.9 J/°C)
= 143.59°C
But, since the sample of Zinc lost heat then the temperature change will have a negative value.
ΔT = -143.59°C
Then,
ΔT = T(final) - T(initial)
Therefore,
T(initial) = T(final) - ΔT
= 100°C - (-143.59°C)
= 243.59°C
Hence, the initial temperature of zinc sample is 243.59°C
Answer: Yes, if there are more shells the nuclear charge decreases.
Answer:
Fe2(SO4)3 + 3BaCl2 → 2FeCl3 + 3BaSO4
Answer:
2.15 mg of uranium-238 decays
Explanation:
For decay of radioactive nuclide-
where N is amount of radioactive nuclide after t time, 
is initial amount of radioactive nuclide and 
is half life of radioactive nuclide
Here 
, 
and 
So,
so, N = 2.446 mg
mass of uranium-238 decays = (4.60-2.446) mg = 2.15 mg
