The manner of death is how the death came about. A natural death occurs as a result of aging, illness, or disease. ... A homicide occurs when death is caused by another person.
Answer:
pure hydrogen is a pure substance even though it consists of many different types of molecules. what makes it pure substance is that it is free from contamination.
Answer : The standard enthalpy of formation of ethylene is, 52.4 kJ
Explanation :
According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.
According to this law, the chemical equation can be treated as ordinary algebraic expression and can be added or subtracted to yield the required equation. That means the enthalpy change of the overall reaction is the sum of the enthalpy changes of the intermediate reactions.
The formation reaction of
will be,

The intermediate balanced chemical reaction will be,
(1)

(2)

(3)

Now we will reverse the reaction 1, multiply reaction 2 and 3 by 2 then adding all the equation, we get :
(1)

(2)

(3)

The expression for enthalpy of formation of
will be,



Therefore, the standard enthalpy of formation of ethylene is, 52.4 kJ
Answer:
The pressure changes from 2.13 atm to 1.80 atm.
Explanation:
Given data:
Initial pressure = ?
Final pressure = 1.80 atm
Initial temperature = 86.0°C (86.0 + 273 = 359 K)
Final temperature = 30.0°C (30+273 =303 K)
Solution:
According to Gay-Lussac Law,
The pressure of given amount of a gas is directly proportional to its temperature at constant volume and number of moles.
Mathematical relationship:
P₁/T₁ = P₂/T₂
Now we will put the values in formula:
P₁ = P₂T₁ /T₂
P₁ = 1.80 atm × 359 K / 303 K
P₁ = 646.2 atm. K /303 K
P₁ = 2.13 atm
The pressure changes from 2.13 atm to 1.80 atm.