Answer: The chemical equation for the formation one mole of
from its elements in their standard states is 
Explanation:
The standard enthalpy of formation or standard heat of formation of a compound is the change of enthalpy during the formation of 1 mole of the substance from its constituent elements, with all substances in their standard states.
The chemical equation for the formation one mole of
from its elements in their standard states is:

where (s) represents solid state and (g) represents gaseous state.
Answer:
When fuels are incompletely burnt, they release carbon monoxide gas into the atmosphere. This gas is very dangerous as it is poisonous in nature
Explanation:
Answer: December
Explanation:
The winter solstice is around December 21, marking the date on which the Sun is lowest in the sky at noon and rises and sets farthest south.
Answer:
SeF4 is a polar molecule
Explanation:
SeF4 is a polar molecule because a polar molecule is any molecule that have lone pairs of electrons in the central atom or have atoms that are electronegative and the electrons between that are covalently bonded are not evenly distributed.
The electronegative atoms of flourine in SeF4 are not evenly distributed and kind pairs of electrons are on the central atom.
Answer:
Kc for this reaction is 0.43
Explanation:
This is the equilibrium:
N₂(g) + 2H₂O(g) → 2NO(g) +2H₂(g)
And we have all the concentration at equilibrium:
N₂: 0.25M
H₂ : 1.3M
NO: 0.33M
H₂: 1.2M
They are ok, because they are in MOLARITY. (mol/L)
Let's make the expression for Kc
Kc = ( [NO]² . [H₂]² ) / ([N₂] . [H₂O]²)
Kc = (0.33² . 1.2²) / (0.25 . 1.2²)
Kc = 0.4356
In two significant digits. 0.43