Answer:
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- <u><em>C) How much energy was added to the substance to increase molecule motion? </em></u>
Explanation:
<em>The most relevant question to ask regarding this change</em> must take into account the physical knowledge about matter.
When matter changes from<em> liquid </em>state to <em>gaseous</em> state, a physical change called evaporation, the particles (molecules or atoms) of the <em>pure substance </em>will separate from each other, take up more space and move faster.
<em>Condensation</em> is the opposite to evaporation, thus the option A) is not the most relevant question.
<em>The charge of the particles</em> does not change; so the option B) is not relevant at all.
The particles should gain energy from the surroundings to <em>increase</em> their <em>motion</em> (kinetic energy) when they pass from liquid state, where they move slower, to gas state, where they move faster. Hence, the option<em> C), How much energy was added to the substance to increase molecule motion?</em> , is totally relevant.
Since this is an increase in the <em>kinetic energy of the molecules</em>, the option D) is not relevant.
Answer:
First one is: ammonia
Second one is: calcium hydroxide
Explanation:
D:
When electrons are gained, the charge of the atom decreases.
When you are given an atom with a charge, the oxidation of that atom is the charge. So by going from a Cr^3+ (Oxidation Number = 3) to a Cr^2+ (Oxidation Number = 2), the Oxidation Number thus decreases.
The answer is c how much mass per unit of volume is in a substance
Answer:

Explanation:
![\Delta H_{rxn}=\sum [n_{i}\times \Delta H_{f}^{0}(product)_{i}]-\sum [n_{j}\times \Delta H_{f}^{0}(reactant_{j})]](https://tex.z-dn.net/?f=%5CDelta%20H_%7Brxn%7D%3D%5Csum%20%5Bn_%7Bi%7D%5Ctimes%20%5CDelta%20H_%7Bf%7D%5E%7B0%7D%28product%29_%7Bi%7D%5D-%5Csum%20%5Bn_%7Bj%7D%5Ctimes%20%5CDelta%20H_%7Bf%7D%5E%7B0%7D%28reactant_%7Bj%7D%29%5D)
Where
and
are number of moles of product and reactant respectively (equal to their stoichiometric coefficient).
is standard heat of formation.
So, ![\Delta H_{rxn}=[2mol\times \Delta H_{f}^{0}(CO_{2})_{g}]+[3mol\times \Delta H_{f}^{0}(H_{2}O)_{g}]-[1mol\times \Delta H_{f}^{0}(C_{2}H_{5}OH)_{l}]-[3mol\times \Delta H_{f}^{0}(O_{2})_{g}]](https://tex.z-dn.net/?f=%5CDelta%20H_%7Brxn%7D%3D%5B2mol%5Ctimes%20%5CDelta%20H_%7Bf%7D%5E%7B0%7D%28CO_%7B2%7D%29_%7Bg%7D%5D%2B%5B3mol%5Ctimes%20%5CDelta%20H_%7Bf%7D%5E%7B0%7D%28H_%7B2%7DO%29_%7Bg%7D%5D-%5B1mol%5Ctimes%20%5CDelta%20H_%7Bf%7D%5E%7B0%7D%28C_%7B2%7DH_%7B5%7DOH%29_%7Bl%7D%5D-%5B3mol%5Ctimes%20%5CDelta%20H_%7Bf%7D%5E%7B0%7D%28O_%7B2%7D%29_%7Bg%7D%5D)
or, ![\Delta H_{rxn}=[2mol\times -393.509kJ/mol]+[3mol\times -241.818kJ/mol]-[1mol\times -277.69kJ/mol]-[3mol\times 0kJ/mol]](https://tex.z-dn.net/?f=%5CDelta%20H_%7Brxn%7D%3D%5B2mol%5Ctimes%20-393.509kJ%2Fmol%5D%2B%5B3mol%5Ctimes%20-241.818kJ%2Fmol%5D-%5B1mol%5Ctimes%20-277.69kJ%2Fmol%5D-%5B3mol%5Ctimes%200kJ%2Fmol%5D)
or, 