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State the crystal structures of SiO2 and CO2 and why one has a higher melting point than the other.

SiO 2 forms a giant covalent structure while CO 2 has a simple molecular structure.In the giant covalent structure of SiO 2 , strong covalent bonds hold the atoms together in the structure, while CO 2 has on...
FT
Answered by Fabian T. • Chemistry tutor
35767 Views

Please could you explain to me when past participles must agree when using the passé composé? (NB in my experience, this was an issue for A-Level students of French too)

There are two cases when the past participle must agree in both gender and number in French. The first is when we use être as the 'auxiliary verb'. If we were to say, 'this man died', in French we would say ...
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Answered by Chris C. • French tutor
3294 Views

How do I generate the perfect tense in Spanish?

The perfect tense (eg. to have done something) in Spanish functions exactly as it does in English. We take the verb haber, which works like 'to have' in English and conjugate it:(yo) he(tú) has(él/ella/usted...
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Answered by Chris C. • Spanish tutor
2270 Views

I do 400J of work compressing a gas, but I maintain the same temperature. What is the delta U, Q and W in this case?

U = 0Q = -400W = -400
HC
Answered by Helen C. • Physics tutor
2830 Views

Outline the problem of evil and one possible response to it.

The problem of evil is one that is often thought to come in two forms - the logical and the evidential - both of which arrived at due to the Christian devotion to the idea of a God of all perfections (i.e. a...
TH
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