I would say when an atom has its valence electron shell filled like a noble gas has, it is not easily changed.
I’m not entirely sure of what you’re asking, but if you’re talking about bonding then it would be an ionic bond that is not easily changed.
A controlled investigation is a experiment that is set for example the same rule for everything
Hope this helps
A catalyst is a substance that increases the rate of a chemical reaction without itself being consumed . (ans: second choice)
Answer:
1.71 kJ/mol
Explanation:
The expression for the calculation of the enthalpy change of a process is shown below as:-
Where,
is the enthalpy change
m is the mass
C is the specific heat capacity
is the temperature change
Thus, given that:-
Mass of CaO = 1.045 g
Specific heat = 4.18 J/g°C
So,
Also, 1 J = 0.001 kJ
So,

Also, Molar mass of CaO = 56.0774 g/mol

Thus, Enthalpy change in kJ/mol is:-

climate
Changes in the composition of the atmosphere have caused gradual changes in earth's <u>climate</u> throughout history, causing changes in plant and animal life that contributed to mass extinctions.
The following are some of the reasons:
- UV light
- climate
- pollutants
- hydrofluorocarbons
heat
- The surface of the Earth warms up as sunlight strikes it.
- Surface-emitted infrared light is absorbed in the atmosphere and transformed into heat.
- The temperature close to the surface rises as a result of this heat being trapped in the atmosphere.
<h3>UV light:</h3>
- indirect impacts of climate change on UV radiation from the surface.
- By changing the concentrations of ozone, UV-absorbing tropospheric gases, aerosols, and clouds in the atmosphere, climate change may have indirectly affected UV radiation levels in the past.
- These influences are probably going to persist in the future.
<h3>climate:</h3>
- People are at risk from food and water shortages, greater flooding, high heat, an increase in disease, and economic loss due to climate change.
- Conflict and human migration are potential outcomes.
- Climate change is the top hazard to world health in the twenty-first century, according to the World Health Organization (WHO).
<h3>pollutants:</h3>
- these are also resulting in the increase of temperature of the Earth and is also damaging ozone layer.
To learn more about the changes in earth visit:
brainly.com/question/13434833?
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