Answer : The standard enthalpy of formation of methane is, -74.8 kJ/mole
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 3 by 2 then adding all the equations, we get :
(1) 
(2)
(3) 
The expression for enthalpy of formation of will be,
Therefore, the standard enthalpy of formation of methane is, -74.8 kJ/mole
Answer:
the atomic mass of the element with 37 protons,43 neutrons and 36 electrons is 80
Answer: really hard
Explanation: I wish I knew how to help you
It would be copper and iron -A
Answer:
Option-1 (Solubility and Molecular polarity) is the correct answer.
Explanation:
Thin Layer Chromatography is employed to separate a mixture of non volatile compounds. In this technique an adsorbent material like silica gel is coated on a plastic, glass or aluminium sheet. Then the mixture of compounds is applied at the bottom of sheet and the sheet is placed in the container containing a solvent system. It is observed that the solvent starts travelling upward through capillary action.
While the solvent is running the mixture of compounds starts separating from each other. This separation is due to following physical properties.
1) Solubility of Mixture in Solvent:
In a mixture those compounds which has more solubility in solvent will travel more and will give greater Rf value and the less soluble will left behind with smaller Rf value. Hence due to solubility a mixture of compounds can be separated.
2) Polarity of Molecules:
As the stationary phase (adsorbent material) is polar in nature, so in mixture those compounds which are less polar will less interact with the stationary phase and will travel more with greater Rf value, while, more polar molecules will form stronger interactions with the stationary phase, hence will travel less and therefore, will show smaller Rf values.
