<u>Answer:</u> The correct answer is Option A.
<u>Explanation:</u>
Standard enthalpy of formation is the change in enthalpy of one mole of a substance present at the standard state that is 1 atm of pressure and 298 K of temperature. The substance is formed from its pure elements under the same conditions.
We are given a chemical compound having chemical formula 
This compound is formed by the combination of calcium, nitrogen and oxygen elements.
The chemical equation for the formation of from the components in their standard states follows:
Hence, the correct answer is Option A.
Pure water does
not have enough ions to conduct electricity. A mixture of metals such as iron,
zinc and copper in the wet soil can trigger electrolysis that requires excess
energy in the form of over potential to conduct electricity. The excess energy
is needed due to limited self-ionization of water. The wet soil then can
conduct current when positive and negative ions are present. The water ions begin
to flow from anode (positive electrode) to cathode (negative electrode) to be oxidize
and produce electricity.
<span> </span>
Answer: The molecular formula will be 
Explanation:
If percentage are given then we are taking total mass is 100 grams.
So, the mass of each element is equal to the percentage given.
Mass of C= 70.6 g
Mass of H = 5.9 g
Mass of O = 23.5 g
Step 1 : convert given masses into moles.
Moles of C =
Moles of H =
Moles of O =
Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.
For C = 
For H =
For O =
The ratio of C : H: O= 4: 4:1
Hence the empirical formula is 
The empirical weight of = 4(12)+4(1)+1(16)= 68g.
The molecular weight = 136 g/mole
Now we have to calculate the molecular formula.
The molecular formula will be=
Answer:
Vaporization
Explanation:
Vaporization is the change of a specie to the gaseous state. To 'disappear' in this case simply means to change to the gaseous state.
Substances with high vapour pressure tend to be easily converted to vapour phase. Hence if Glade air freshener gel 'disappears' easily, then it has a high vapour pressure and is easily converted to vapour (gas).
