Answer:
MgO has a highest melting point
C5Br has lowesst
Explanation:
It takes a lot of energy to overcome the strong electrostatic forces of attraction between oppositely charged ions, so ionic compounds have high melting and boiling points. ... Magnesium oxide is made from ions with two charges (Mg 2+ and O 2-) and so has a much higher melting point of 2852°C.
Answer:

Explanation:
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In this case, since we can see that the heat released by the combustion of the mayonnaise is absorbed by the bomb calorimeter and water, we can set up the following equation:

Whereas q for mayonnaise stands for the heat due to its usage; thus, we plug in to obtain:

Now, if 10.0 g are eaten, the energy provided by it turns out:

And we need that value in dietary calories, 1 kcal:

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Answer:

Explanation:
You calculate the energy required to break all the bonds in the reactants.
Then you subtract the energy needed to break all the bonds in the products.
CH₃CH₂OH + 3O₂ ⟶ 2CO₂ + 3H₂O
Bonds: 5C-H 1C-C 1C-O 1O-H 3O=O 4C=O 6O-H
D/kJ·mol⁻¹: 413 347 358 467 495 799 467

The correct answer is reactants 2Na and 2H₂O and products 2NaOH and 1H₂.
The given unbalanced chemical equation is:
Na (s) + H2O (l) → NaOH (aq) + H₂ (g)
From the equation, it can be seen that there are three atoms of hydrogen on the products side, however, only two on the reactant's side. So, in order to balance the equation, one needs to multiply the sodium hydroxide by 2 to get a total of 4 atoms of hydrogen on the product's side.
This will enable one to readily double the number of molecules of water to get 4 atoms of hydrogen on the reactants side, and then balance the atoms of sodium by multiplying the sodium metal by 2. The balanced equation obtained is:
2Na (s) + 2H₂O (l) → 2NaOH (aq) + H₂ (g)