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Predict whether the lattice energy of magnesium oxide, MgO, is more or less exothermic than the lattice energy of magnesium sulfide, MgS. Justify your answer in terms of the sizes and the charges of the ions involved.

To start with, we can clearly see that the difference between MgO and MgS is the anions, we have O(2-) and S(2-). As we know (from looking at the periodic table) O(2-) has a smaller ionic radius, and thereby...
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Answered by Huzair A. • Chemistry tutor
21266 Views

When should I use "qui" and when should I use "que"?

A relative pronoun, such as “qui” or “que” , is a word that is used to connect two parts of a sentence together when referring to someone or something that has already been mentioned earlier in the sentence....
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Answered by William O. • French tutor
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Define a hydrocarbon and explain the difference between alkenes and alkanes.

A Hydrocarbon is an organic molecule containing only hydrogen and carbon atoms. Alkanes are saturated hydrocarbons, meaning they are only made up of single bonds. The carbons are 'saturated' with hydrogen at...
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Answered by Saskia H. • Chemistry tutor
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When a new antigen is presented to the immune system, an immune response leads to antibodies are released. The second time this happens it is much faster - explain why

In the primary immune response, there is antigen presentation followed by clonal selection, expansion and differentiation of helper t cells. This leads to plasma cells releasing antibodies and the developmen...
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Answered by Maxine R. • Biology tutor
3464 Views

How do I use the imperfect and preterite tenses together to describe a completed event?

Well, let's start with an example. ej. Estaba atravesando la calle y de repente un coche se estralló contra un árbol. (ex. I was crossing the road and all of a sudden a car crashed into a tree.)This is a typ...
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Answered by Gregory K. • Spanish tutor
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