<u>Answer:</u> The empirical formula for the given compound is 
<u>Explanation:</u>
We are given:
Percentage of H = 5.80 %
Percentage of O = 23.02 %
Percentage of N = 20.16 %
Percentage of Cl = 51.02 %
Let the mass of compound be 100 g. So, percentages given are taken as mass.
Mass of H = 5.80 g
Mass of O = 23.02 g
Mass of N = 20.16 g
Mass of Cl = 51.02 g
To formulate the empirical formula, we need to follow some steps:
- <u>Step 1:</u> Converting the given masses into moles.
Moles of Hydrogen = 
Moles of Oxygen = 
Moles of Nitrogen = 
Moles of Chlorine = 
- <u>Step 2:</u> Calculating the mole ratio of the given elements.
For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 1.44 moles.
For Hydrogen = 
For Oxygen = 
For Nitrogen = 
For Chlorine = 
- <u>Step 3:</u> Taking the mole ratio as their subscripts.
The ratio of H : O : N : Cl = 4 : 1 : 1 : 1
Hence, the empirical formula for the given compound is 
Explanation:
Moles of metal,
=
4.86
⋅
g
24.305
⋅
g
⋅
m
o
l
−
1
=
0.200
m
o
l
.
Moles of
H
C
l
=
100
⋅
c
m
−
3
×
2.00
⋅
m
o
l
⋅
d
m
−
3
=
0.200
m
o
l
Clearly, the acid is in deficiency ; i.e. it is the limiting reagent, because the equation above specifies that that 2 equiv of HCl are required for each equiv of metal.
So if
0.200
m
o
l
acid react, then (by the stoichiometry), 1/2 this quantity, i.e.
0.100
m
o
l
of dihydrogen will evolve.
So,
0.100
m
o
l
dihydrogen are evolved; this has a mass of
0.100
⋅
m
o
l
×
2.00
⋅
g
⋅
m
o
l
−
1
=
?
?
g
.
If 1 mol dihydrogen gas occupies
24.5
d
m
3
at room temperature and pressure, what will be the VOLUME of gas evolved?
Answer:

Explanation:
First of all we need to calculate the heat that the water in the cooler is able to release:

Where:
- Cp is the mass heat capacity of water
- V is the volume
is the density


To calculate the mass of CO2 that sublimes:

Knowing that the enthalpy of sublimation for the CO2 is: 


B- 8.2980
C- 11.2603
F- 17.4228
Li- 5.3917
Na- 5.1391
I would say your answer is Na.