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

SiO₂ forms a giant covalent structure while CO₂ has a simple molecular structure.In the giant covalent structure of SiO₂, strong covalent bonds hold the atoms together in...

Answered by Fabian T. • Chemistry tutor

28307 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 s...

Answered by Chris C. • French tutor

2090 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/us...

Answered by Chris C. • Spanish tutor

1531 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

Answered by Helen C. • Physics tutor

1987 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...

Answered by Tommy H. • Religious Studies tutor

3624 Views