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Explain why water molecules form on average two hydrogen bonds per molecule, whereas ammonia molecules (NH3) form only one.

A hydrogen bond requires both a lone pair of electrons on a O, N or F atom and a hydrogen atom. In water there are two lone pairs and two hydrogen atoms, allowing the formation of two hydrogen bonds. In ammo...
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‘Tacitus’ historiography seeks to establish an accurate and impartial presentation of the principate’ discuss.

To some degree Tacitus seeks to establish an accurate presentation of the principate in Annals I , and this is evidenced through his engagement with contemporary sources and references to widely known events...
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What is food security?

Food security is a measure of someone's access to safe and nutritious food. Good food security implies that an individual has a sustainable supply of food available to them that will allow them to lead a hea...
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If the velocity of a particle is given by t^2+t, then determine the acceleration of the particle when t=4.

To get from velocity to acceleration, you must derivate the velocity equation. This is because acceleration is the rate at which velocity changes so to change the velocity into acceleration it must be derive...
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How do I check if events are independent (in statistics / probability)?

The sentence 'event A is independent to event B' means that the probability of A does not affect the probability of event B. In mathematical terms, this can be written as:Prob(A and B) = Prob(A) x Prob(B) So...
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