Answer:
Carbon dioxide (CO₂) is an important green house gas. A small increase in the concentration of this gas can lead to the global rise in the surface temperature. Over the last 100 years, this gas has increased significantly. One of the main cause behind this the anthropogenic activities.
After the setup of the industrial revolution, there has been a large increase in this CO₂ concentration, as there are numerous large factories and indutries that releases this harmful gases. In addition to this, the burning up of fossil fuel also is responsible for the emission of large amount of carbon into the atmosphere.
Deforestation also is another cause, because trees are no longer there in vast quantities which takes up a large number of atmospheric carbon and in return liberates plenty of oxygen.
Thus, the activities done by man over the last century has led to the increase in the concentration of CO₂ into the atmosphere.
Answer:
B
Explanation:
This is because exothermic reactions occurs when bnds are formed, and involves the release of energy.
Endothermic reaction occur when bonds are broken,and involves absorption of energy.
<u>Answer:</u> The 
for the reaction is 51.8 kJ.
<u>Explanation:</u>
Hess’s law of constant heat summation states that the amount of heat absorbed or evolved in a given chemical equation remains the same whether the process occurs in one step or several steps.
According to this law, the chemical equation is treated as ordinary algebraic expressions and can be added or subtracted to yield the required equation. This means that the enthalpy change of the overall reaction is equal to the sum of the enthalpy changes of the intermediate reactions.
The chemical equation for the reaction of carbon and water follows:
The intermediate balanced chemical reaction are:
(1) 
( × 2)
(2) 
( × 2)
(3) 
The expression for enthalpy of the reaction follows:
![\Delta H^o_{rxn}=[2\times \Delta H_1]+[2\times \Delta H_2]+[1\times (-\Delta H_3)]](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Brxn%7D%3D%5B2%5Ctimes%20%5CDelta%20H_1%5D%2B%5B2%5Ctimes%20%5CDelta%20H_2%5D%2B%5B1%5Ctimes%20%28-%5CDelta%20H_3%29%5D)
Putting values in above equation, we get:
![\Delta H^o_{rxn}=[(2\times (-393.7))+(2\times (-285.9))+(1\times -(-1411))]=51.8kJ](https://tex.z-dn.net/?f=%5CDelta%20H%5Eo_%7Brxn%7D%3D%5B%282%5Ctimes%20%28-393.7%29%29%2B%282%5Ctimes%20%28-285.9%29%29%2B%281%5Ctimes%20-%28-1411%29%29%5D%3D51.8kJ)
Hence, the for the reaction is 51.8 kJ.
Sun spots- dark circles on the sun’s surface that I believe are areas of cooler temperatures.
Solar flares- arcs of fire that leap from the sun’s surface. Nothing special, they’re a daily roumaine for the sun
1. Na3PO4+Mg(NO3)2= NaNO3 + MgPO4
So this is not the answer.
2. Al+CuCl2= AlCl3+ Cu
So this is the answer.
3. Mg+O2= MgO2
So this is not an answer
4. Cl2+KI= KCl+I2
So this is also an answer
Hence B and C are answers
