Answer:
-7.34 kilo Joules is the change in enthaply when 20.0 grams of nitrogen triiodide decomposes.
Explanation:
Mass of nitrogen triiodide = 20.0 g
Moles of nitrogen triiodide = 

According to reaction, 2 moles of nitrogen triiodide gives 290.0 kilo Joules of heat on decomposition ,then 0.05063 moles of nitrogen triiodide will give :

-7.34 kilo Joules is the change in enthaply when 20.0 grams of nitrogen triiodide decomposes.
Answer:
HCl
Explanation:
<em>Choices:</em>
<em>CO: 28.01g/mol</em>
<em>NO₂: 46g/mol</em>
<em>CH₄: 16.04g/mol</em>
<em>HCl: 36.4g/mol</em>
<em>CO₂: 44.01g/mol</em>
<em />
It is possible to identify a substance finding its molar mass (That is, the ratio between its mass in grams and its moles). It is possible to find the moles of the gas using general ideal gas law:
PV = nRT
<em>Where P is pressure of gas 0.764atm; V its volume, 0.279L; n moles; R gas constant: 0.082atmL/molK and T its absolute temperature, 295.85K (22.7°C + 273.15).</em>
Replacing:
PV = nRT
PV / RT = n
0.764atm*0.279L / 0.082atmL/molKₓ295.85K = n
<em>8.786x10⁻³ = moles of the gas</em>
<em />
As the mass of the gas is 0.320g; its molar mass is:
0.320g / 8.786x10⁻³moles = 36.4 g/mol
Based in the group of answer choices, the identity of the gas is:
<h3>HCl</h3>
<em />
Conductivity, malleability, and high melting points. Hope this helps :)
I think maybe reptiles bu i could be wrong. :)