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3 years ago

Please Help!!!!!!!!!!!!!!!!!!!!

Chemistry

2 answers:

mote1985 [20]3 years ago

7 0

Answer; picture 1

Explanation; presence of vegetation

Alekssandra [29.7K]3 years ago

5 0

Answer: first one

Explanation:

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Rn-222 has a half-life of 3.82 days. If 25.0 g of Radon-22 was originally present, approximately how many grams would be left af

horsena [70]

Answer:

Approximately 0.39 g or 0.4 g if you're rounding up

Explanation:

15/3.82 = 3.92

Let's round that up to 4

That means 15 days is around 4 half lives

4 half lives means 1/16 of the original mass will be left

25/16 = 0.390625

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3 years ago

Describe the two methods of active transport

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Endocytosis
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Exocytosis
Secretion of material out of the plasma membrane

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3 years ago

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Which change would most likely increase the resistance in the circuit ?

yaroslaw [1]

Answer:

I think it would be C but don't quote me on it

Explanation:

It adds another obstacle for the current to go through

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2 years ago

which of the following would represent an addition to a nation’s gdp a) ms. jone purchases a share of stock in a technology star

Elodia [21]

c) the government hires workers to install street lights

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2 years ago

How many grams of H20 are produced from the reaction of 30.0g of Mg(OH)2 reacting with

Anna35 [415]

<u>Answer:</u> The mass of water required is 18.52 g

<u>Explanation:</u>

The number of moles is defined as the ratio of the mass of a substance to its molar mass.

The equation used is:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ......(1)

Given mass of magnesium hydroxide = 30.0 g

Molar mass of magnesium hydroxide = 58.32 g/mol

Plugging values in equation 1:

$\text{Moles of magnesium hydroxide}=\frac{30.0g}{58.32g/mol}=0.5144 mol$

The given chemical equation follows:

$Mg(OH)_2+2HCl\rightarrow MgCl_2+2H_2O$

By the stoichiometry of the reaction:

If 1 mole of magnesium hydroxide produces 2 moles of water

So, 0.5144 moles of magnesium hydroxide will react with = $\frac{2}{1}\times 0.5144=1.0288mol$ of water

Molar mass of water = 18 g/mol

Plugging values in equation 1:

$\text{Mass of water}=(1.0288mol\times 18g/mol)=18.52g$

Hence, the mass of water required is 18.52 g

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2 years ago