D) Physical Change, I would argue, because you can reverse this change by boiling off (evaporating) the water. But there are arguments for both physical and chemical change being what occurs.
A physical change results in a change of the material's appearance, but no new chemical products result. A chemical change involves a chemical reaction, with new substances produced as a result of the change.
The atmosphere is a mixture of gasses that surrounds a planet, moon, or other celestial body
Answer:
429.4 kJ are absorbed in the endothermic reaction.
Explanation:
The balanced chemical equation tells us that 1168 kJ of heat are absorbed in the reaction when 4 mol of NH₃ (g) react with 5 mol O₂ (g).
So what we need is to calculates how many moles represent 25 g NH₃(g) and calculate the heat absorbed. (NH₃ is the limiting reagent)
Molar Mass NH₃ = 17.03 g/mol
mol NH₃ = 25.00 g/ 17.03 g/mol = 1.47 mol
1168 kJ /4 mol NH₃ x 1.47 mol NH₃ = 429.4 kJ
Answer: 
Explanation:
First we have to calculate the heat absorbed by bomb calorimeter
Formula used :
= heat absorbed by calorimeter = ?
= specific heat of = 10.69 kJ/K
= final temperature = 
= initial temperature = 
As heat absorbed by calorimeter is equal to the heat released by acetylene during combustion.
Thus 1.53 gram of acetylene releases heat of combustion = 258.7kJ
So, 26.04 g/mole of acetylene releases heat of combustion 
Therefore, the heat of combustion of acetylene is,
A physical change changes the state on object is in, making the answer A) iron melting. Since it's melting, it's going from solid to liquid.
