Volume = 3 cm × 3cm × 3cm
= 27 cm ³
Mass = 213 g
Density =
= <span>

</span>
<span> = 7.89 g / cm³
Thus answer is D.</span>
The density of the sample : 0.827 g/L
<h3>Further explanation</h3>
In general, the gas equation can be written

where
P = pressure, atm , N/m²
V = volume, liter
n = number of moles
R = gas constant = 0.082 l.atm / mol K (P= atm, v= liter),or 8,314 J/mol K (P=Pa or N/m2, v= m³)
T = temperature, Kelvin
n= 1 mol
MW Neon = 20,1797 g/mol
mass of Neon :

The density of the sample :

or We can use the ideal gas formula ta find density :

Answer: a)neptunium b) the element is unstable
Explanation:
a) 238 0 239 -1
U + n = Np e
92 1 93 0
b) it is an isotope of neptunium with half-lives less than 4.5 days, with most less than 50 minutes. It is therefore not stable that's why they where unable to identify it
Answer:
c tarnishes in air
Explanation:
After silver has been exposed to air that contains sulphur gases, discoloration would occur. there would be darkening that is caused by the reaction with gases.When any silver object tarnishes, it brings about a disfiguring of that object. Hydrogen sulphide would be needed for this to happen. silver sulphide is black and a if a thin layer should form on any surface, it ill darken it. This is what we refer to as tarnishing.