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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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By what process do electromagnetic waves release from the materials they contact?
Rudik [331]

Answer:

The photoelectric effect

Explanation:  hope it helps

5 0
3 years ago
How many milliliters of 4.00 M NaOH are required to exactly neutralize 50.0 milliliters of a 2.00 M solution of HNO3 ?
kramer

Answer: The volume of NaOH required is 25.0 ml

Explanation:

According to the neutralization law,

n_1M_1V_1=n_2M_2V_2

where,

n_1 = basicity HNO_3 = 1

M_1 = molarity of HNO_3 solution = 2.00 M

V_1 = volume of  HNO_3 solution = 50.0 ml

n_2 = acidity of NaOH = 1

M_1 = molarity of NaOH solution = 4.00 M

V_1 = volume of  NaOH solution =  ?

Putting in the values we get:

1\times 2.00\times 50.0=1\times 4.00\times V_2

V_2=25.0ml

Therefore, volume of NaOH required is 25.0 ml

3 0
3 years ago
Four flasks are prepared, each containing 100mL of aqueous solutions of equal concentration. Which solution has the lowest freez
Jet001 [13]
The freezing point depression is a colligative property which means that it is proportional to the number of particles dissolved.

The number of particles dissolved depends on the dissociation constant of the solutes, when theyt are ionic substances.

If you have equal concentrations of two solutions on of which is of a ionic compound and the other not, then the ionic soluton will contain more particles (ions) and so its freezing point will decrease more (will be lower at end).   

In this way you can compare the freezing points of solutions of KCl, Ch3OH, Ba(OH)2, and CH3COOH, which have the same concentration.

As I explained the solution that produces more ions will exhibit the greates depression of the freezing point, leading to the lowest freezing point.

In this case, Ba(OH)2 will produce 3 iones, while KCl will produce 2, CH3OH will not dissociate into ions, and CH3COOH will have a low dissociation constant.

Answer: Then, you can predict that Ba(OH)2 solution has the lowest freezing point.
6 0
3 years ago
When light strikes chlorophyll molecules, they lose electrons, which are ultimately replaced by other electrons obtained by ____
fomenos
The answer is by "splitting water".

hope this helps
5 0
3 years ago
Select the ion.<br><br>1)Cu<br>2)PO4-3<br>3)SO2
Lilit [14]
I believe the answer is B. PO4-3
6 0
3 years ago
Read 2 more answers
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