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padilas [110]
3 years ago
11

What was discovered first helium or samarium?

Chemistry
1 answer:
lana [24]3 years ago
7 0
The correct answer is helium, but both discoveries were quite close. Helium was discovered in 1868 during a solar eclipse by French astronomer Jules Janssen, while samarium was discovered in 1879 by a French chemist Paul Émile Lecoq de Boisbaudran.
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Digoxin is available in a concentration of 0.1 mg/ml. How many ml are required to administer a 75 mcg dose?
Step2247 [10]

Answer : The volume required to administer a 75 mcg dose are, 0.75 mL

Explanation : Given,

Concentration of Digoxin = 0.1 mg/mL

That means, 0.1 mg of Digoxin present in 1 mL of solution.

Mass of dose = 75 mcg = 0.075 mg

Conversion used : (1 mcg = 0.001 mg)

Now we have to determine the volume required to administer a 75 mcg dose.

As, 0.1 mg of Digoxin required in 1 mL of solution

So, 0.075 mg of Digoxin required in \frac{0.075mg}{0.1mg}\times 1mL=0.75mL of solution

Thus, the volume required to administer a 75 mcg dose are, 0.75 mL

5 0
3 years ago
Earth is approximately 1.5 x 10^8 km from the sun the. How far is earth from the sun meters
Zielflug [23.3K]

Answer:

{ \tt{1 \: km = 1000m}} \\ { \tt{1.5  \times {10}^{8} km =  (\frac{1.5 \times  {10}^{8} \times 1000 }{1} )m}} \\  = 1.5 \times  {10}^{11}  \: metres

4 0
3 years ago
Type the correct answer in the box. Express your answer to three significant figures. Iron(II) chloride and sodium carbonate rea
Ad libitum [116K]

Answer:

The reaction can produce 287 grams of iron(II) carbonate

Explanation:

To solve this question we must find the moles of iron(II) chloride that react. Using the chemical equation we can find the moles of iron(II) carbonate and its mass -Molar mass FeCO3: 115.854g/mol-

<em>Moles FeCl2:</em>

1.24L * (2.00mol / L) = 2.48 moles FeCl2

As 1 mol FeCl2 produce 1 mol FeCO3, the moles of FeCO3 = 2.48 moles

<em>Mass FeCO3:</em>

2.48mol * (115.854g / mol) =

<h3>The reaction can produce 287 grams of iron(II) carbonate</h3>
5 0
3 years ago
if 10.8 moles of hydrogen gas are consumed how many moles of nitrogen gas werw consumed in the reaction
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<em><u>Answer:</u></em>

<h3>look at the balanced chemical equation for this synthesis reaction </h3><h3> S mole ratio between nitrogen gas and hydrogen gas. This means that, regardless of how many moles of nitrogen gas you have, the reaction will always consume twice as many moles of hydrogen gas.</h3><h3 />
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4 years ago
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