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.
From the Graham's law of effusion;
R1/R2 = √MM2/√MM1
Molar mass of chlorine gas is 71
Therefore;
1.87= √ 71 /√mm1
= 1.87² = 71/mm1
mm1 = 71/1.87²
= 71/3.4969
= 20.3
Thus, the molar mass of the other gas is 20.3 , and i think the gas is neon
Answer: The pressure of the He is 2.97 atm
Explanation:
According to Dalton's law, the total pressure is the sum of individual pressures.
Given :
=total pressure of gases = 6.50 atm
= partial pressure of Nitrogen = 1.23 atm
= partial pressure of oxygen = 2.3 atm
= partial pressure of Helium = ?
putting in the values we get:
The pressure of the He is 2.97 atm