dim? im not so fluent in this but i did research yesterday
Answer:
The answer is: (a) positive; (b) negative.
Explanation:
The change in enthalpy (ΔH) of a reaction is the amount of energy absorbed or released during a chemical reaction carried out at constant pressure.
a) In an endothermic chemical reaction, heat energy is absorbed by the system from the surrounding. Therefore, the sign of enthalpy change for an endothermic process is positive, ΔH= positive.
b) In an exothermic chemical reaction, heat energy is released by the system into the surrounding. Therefore, the sign of enthalpy change for an exothermic process is negative, ΔH= negative.
The answer is false methane is emitted from coal
Option A: Clouds
In the morning, air is cool and as sun begins to rise it starts increasing the temperature of air. By time, the air becomes warmer and warmer. Depending upon the surrounding conditions, air in different areas heat up at different rates.
Due to this heating, thermal formation takes place, this is due to uneven heating of surface of earth. The thermal formation at surface causes difference in temperature of surface of the earth and air around it. The warm air has tendency to rise thus, the air in the thermal rise and expand. Due to expansion it cools down, this process continues till the temperature of thermal air reaches equals to the temperature of surrounding air. This results in the formation of cloud.
Thus, when a humid air mass rises into a cooler temperature area, clouds formation takes place
