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Harrizon [31]
3 years ago
12

What was helium used for in the past?

Chemistry
2 answers:
yawa3891 [41]3 years ago
6 0
Helium used to be used in hot air balloons.  Then, when the Hindenburg exploded, annexed file, they realized that hydrogen was not only lighter, but it also was less flammable.  

Otrada [13]3 years ago
3 0

Hot air balloons. They have a little hot plate/fire or whatever and they used, and that made the helium rise, thus rising the balloon.
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The visible spectrum of the Cr(acac)3
Sati [7]

Explanation:

The observable visible spectrum of Cr(acac)3 complex is different from that of

[Cr(en)3]Br3 due to strength of bonded ligand in the coordination sphere.

en is a strong field ligand compared to acac thus pairing  occurs. In both the complexes

Cr is in +3 state, configuration [Ar] 3d^3. There are 3 unpaired e in Cr(acac)3 whereas 1 unpaired e in [Cr(en)3]Br3 due to pairing.

3 0
3 years ago
Lithium, sodium and potassium are all in group 1 of the periodic table. Which of these has the lowest boiling point?
kvv77 [185]

Answer:

Potassium

Explanation:

In group one of the periodic table both the melting and the boiling points usually decrease down the group.

Now, down the group, it's lithium that comes first, then sodium, then potassium.

Thus, among the 3, potassium is furthermost down the group by virtue of the factor it has the highest atomic number.

Therefore, we can say that potassium has the lowest boiling point among the 3.

5 0
2 years ago
5 atoms Pb to mol Pb
jek_recluse [69]

Answer:

0,83 x 10-²³ mol

Explanation:

n=N/Na

n=5:(6,02 x 10²³)

5 0
3 years ago
The compound methylamine, CH3NH2, is a weak base when dissolved in water. Write the Kb expression for the weak base equilibrium
Veronika [31]

Answer:

Kb = [CH₃NH₃⁺] × [OH⁻] / [CH₃NH₂]

Explanation:

According to Brönsted-Lowry acid-base theory:

  • An acid is a substance that donates H⁺.
  • A base is a substance that accepts H⁺.

When methylamine reacts with water, it behaves as a Brönsted-Lowry base, according to the following reaction.

CH₃NH₂(aq) + H₂O(l) ⇄ CH₃NH₃⁺(aq) + OH⁻(aq)

The basic equilibrium constant (Kb) is:

Kb = [CH₃NH₃⁺] × [OH⁻] / [CH₃NH₂]

3 0
3 years ago
The substances in a chemical reaction that are combined or separated to form new substances are the _______.
katen-ka-za [31]
Reactant/ Reagents and Products
6 0
3 years ago
Read 2 more answers
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