Answer : The enthalpy change for the decomposition of calcium carbonate is, 178.1 kJ/mol
Explanation :
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 given main reaction is,
The intermediate balanced chemical reaction will be,
(1) 
(2) 
(3) 
(4) 
Now we are reversing reaction 1 and then adding reaction 1 and 2, we get :
(1)
(2) 
The expression for enthalpy of change will be,
Thus, the enthalpy change for the decomposition of calcium carbonate is, 178.1 kJ/mol
Answer:- The right choice is A. 
.
Solution:- Latent heat of fusion means the heat required to melt the solid at constant temperature means there is no change in temperature only the solid changes to liquid. So, it is a solid to liquid phase change.
where q is the heat required to convert solid to liquid, m is the mass and 
is the latent heat of fusion.
From given info, 550 kJ that is 550000 J of heat is required to melt 14 kg of solid at 262K temperature. Let's rearrange the equation for latent heat of fusion and plug in the values in it.
= 
If we round this value to two sig figs and write in scientific notations then it becomes .
So, the right choice is A. .
Answer:
2.The cooling effects of more indirect sunlight cause autumn and winter. Because of the Earth's approximately 23.5º tilt, the seasons in the Northern and Southern Hemispheres are reversed, about six months apart from each other.
3.In North America, around June 21, Earth tilts on its axis toward the Sun. That means that at the northern summer solstice, North America will experience summer, and winter will start in in the Southern Hemisphere. Winter Solstice. Around December 21, the Northern Hemisphere tilts the farthest away from the Sun.
Explanation:
