Answer: 
Explanation:
Heat of reaction or enthalpy change is the energy released or absorbed during the course of the reaction.
It is calculated by subtracting the enthalpy of reactants from the enthalpy of products.

= enthalpy change = ?
= enthalpy of products
= enthalpy of reactants
For the given reaction :



Answer:
Then, at some point, these higher energy electrons give up their "extra" energy in the form of a photon of light, and fall back down to their original energy level.
Explanation:
When properly stimulated, electrons in these materials move from a lower level of energy up to a higher level of energy and occupy a different orbital.
Picometre is equal to 1·10⁻¹²m
175·10⁻¹² m = 1,75·10⁻¹⁰ m
Answer:
The sun shines with equal intensity on a farm field, an asphalt road and the ocean. So basically asphalt road are heated the most during the day
Explanation:
The heat of water is more than the specific heat of sand.
Therefore sand is hot.
.Water is reflecting solar radiation.
The land retains more heat since the land absorb solar radiation.
Therefore the land surfaces warm faster.
Since water is a slow conductor of heat, it need more energy than the sand. so its temperature is increasing. soil loses heat faster.
The ocean heats slower than land , the land air is more warmer than lean air. After the sun set the land loses heat quickly .The air above it cools.
Salt can be classified as a pure substance as it is only composed of sodium chloride
while contain many other substances