# Posts by danya

Total # Posts: 7

**Calculus**

I'm reviewing for a test tomorrow and two of the questions on the review had me a little stumped. Lim Sq. Rt.(x+5) - Sq. Rt (5) all divided by X-->0 X I was able to rationalize and ended up with (X)/ x ((sq. rt.(x+5))+ sq. rt.(5)) which gives me 1/ sq. rt.(5)+ sq. rt.(5...

**Chem/ Calculating Lattice Energy, Vapor Pressure**

How do you calculate lattice energy? I have to place the following in order of decreasing magnitude of lattice energy, but I don't know how to do it. KF MgS RbI Is there a formula or some simple way of knowing which has the greatest energy? 2. I also have the same question...

**Chem**

Calculate the amount of grams of carbon dioxide formed from 100 g of octane. The molar mass of octane is 114.33 g/mole. The molar mass of carbon dioxide is 44.0095 g/mole/ 2 C8H18 + 25 O2 ---> 16 CO2 + 18 H20 How do I go about doing this problem? How much would the approach...

**Chemistry**

Determine the end value of n in a hydrogen atom transition, if the electron starts in n=4 and the atom emits a photo of light with a wavelength of 486 nm. *The answer given is 2, but I don't know how they got there.

**Trig**

A sprinkler on a golf green is set to spray water over a distance of 20 meters and to rotate through an angle of 160°. Find the area of the region that can be irrigated with the sprinkler. (Round your answer to two decimal places.) I really have no idea how to go about ...

**Chemistry**

A modern penny weighs 2.5 g but contains only .063 g of copper. How many copper atoms are present in a modern penny? Thanks in advance for any help you can give!

**s.s**

1. Write an essay that compares and contrasts the ways in which China and Japan responded to the West and describes how each nation’s decision to respond to the West affected its domestic and foreign affairs in the years that followed.

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