kg and all the given units are units used to measure mass.
kg is the standard unit to measure mass
lets find the value of 0.00684 kg in all the given units
a. dkg
1 kg is equivalent to 100 decagram (dkg)
therefore 0.00684 kg is = 100 dkg/kg x 0.00684 kg = 0.684 dkg
this is not the given value therefore this choice is incorrect
b. 1 kg is equivalent to 1000 g
therefore 0.00684 kg = 1000 g/kg x 0.00684 kg = 6.84 g
this is the given value so this is correct
c. 1 kg is equivalent to 100 000 centigrams (cg)
therefore 0.00684 kg = 100 000 cg/kg x 0.00684 kg = 684 cg
this is the given value so this is also correct
d) 1 kg is equivalent to 1 000 000 mg
therefore 0.00684 kg = 1 000 000 mg/kg x 0.00684 kg = 6 840 mg
this too is correct
the incorrect answer is A. 0.0684 dkg
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Answer:
The molecular formula = 
Explanation:
Given that:
Mass of compound, m = 0.145 g
Temperature = 200 °C
The conversion of T( °C) to T(K) is shown below:
T(K) = T( °C) + 273.15
So,
T = (200 + 273.15) K = 473.15 K
V = 97.2 mL = 0.0972 L
Pressure = 0.74 atm
Considering,
Using ideal gas equation as:
where,
P is the pressure
V is the volume
m is the mass of the gas
M is the molar mass of the gas
T is the temperature
R is Gas constant having value = 0.0821 L.atm/K.mol
Applying the values in the above equation as:-
The empirical formula is = 
Molecular formulas is the actual number of atoms of each element in the compound while empirical formulas is the simplest or reduced ratio of the elements in the compound.
Thus,
Molecular mass = n × Empirical mass
Where, n is any positive number from 1, 2, 3...
Mass from the Empirical formula = 12 + 1 = 13 g/mol
Molar mass = 78.31 g/mol
So,
Molecular mass = n × Empirical mass
78.31 = n × 13
⇒ n ≅ 6
The molecular formula =
<span>Avogadro's number
represents the number of units in one mole of any substance. This has the value
of 6.022 x 10^23 units / mole. This number can be used to convert the number of
atoms or molecules into number of moles. We do as follows:
</span>10 mol NH3 ( 6.022 x 10^23 molecules / 1 mol ) = 6.022x10^24 molecules NH3
