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vlabodo [156]
3 years ago
5

A radioactive nuclide that is used for geological dating has an atomic number of 19 and mass number 40. Which is the symbol of t

his nuclide?
A 19/21 K
B 21/19 K
C 40/19 K
D 19/40 K
Chemistry
2 answers:
Musya8 [376]3 years ago
5 0
I believe this nuclide is potassium with the symbol K. Atomic number for an element remains constant no matter how the mass changes. From the periodic table, potassium has an atomic number of 19.
Serjik [45]3 years ago
4 0

Answer:

40/19 K or C

Explanation:

edg

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Which climate is most likely found in a high pressure belt
Mice21 [21]

Answer:subtropical highs. ... Near the poles the pressure is high and it is known as the polar high. These pressure belts are not permanent in nature

Explanation: The horse latitudes are subtropical regions known for calm winds and little precipitation. ... Unable to sail and resupply due to lack of wind, crews often ran out of drinking water. To conserve scarce water, sailors on these ships would sometimes throw the horses they were transporting overboard.

Hope this was Helpful

5 0
3 years ago
Calculate the number of O atoms in 0.364 g of CaSO4 · 2H2O
Nikolay [14]

Answer:

<em>= 7.66 x 10²¹  oxygen atoms in 0.364 grams of  CaSO₄·2H₂O</em>

Explanation:

For problems like this posting, one needs an understanding of the following topics:

The definition of the mole

<u>1 mole of substance</u> = mass in grams of substance containing 1 Avogadro's Number ( = 6.023 x 10²³ ) of particles of the specified substance. This is generally one formula weight of the substance of interest. From this, the following equivalent relationships should be memorized:

<em>   1 mole = 1 formula weight = 1 mole weight (g)= 6.023 x 10²³ particles</em>

Converting grams to moles:

<em>Given grams => moles = grams/gram formula wt </em>

Converting moles to grams:

<em>Given moles => grams = moles x gram formula wt</em>

_________________________________________________________

<em>Calculate the number of O atoms in 0.364 g of CaSO₄ · 2H₂O.</em>

Given mass CaSO₄ · 2H₂O = 0.364 grams

Formula Wt CaSO₄ · 2H₂O = 172 g/mole

moles CaSO₄ · 2H₂O = mass <em>CaSO4 · 2H2O / formula Wt. CaSO₄ · 2H₂O</em>

<em>= 0.364 g CaSO₄·2H₂O </em><em>/ </em><em>172 g CaSO4·2H2O </em>

<em>= (0.364/172) mole CaSO₄·2H₂O </em>

<em>= 2.12 x 10⁻³ mole CaSO₄·2H₂O    </em>

<em>∴ number of Oxy (O) atoms in 0.364 grams CaSO₄·2H₂O </em>

<em>=  (2.12 x 10⁻³ mole CaSO₄ · 2H₂O)(6.023 x 10²³ molecules CaSO₄· 2H₂O/ mole)</em>

<em>= 1.276876 x 10²¹molecules CaSO₄· 2H₂O  CaSO₄2H₂O </em>

<em>= 1.276876 x 10²¹ molecules CaSO₄· 2H₂O   x   6 oxygen atoms / molecule</em>

<em>= 7.661256 x 10²¹  oxygen atoms in 0.364 grams of  CaSO₄·2H₂O</em>

<em>= 7.66 x 10²¹  oxygen atoms in 0.364 grams of  CaSO₄·2H₂O</em>

<em />

8 0
2 years ago
Why do group 1 cations form precipitates when mixed with hcl?
Xelga [282]
Both of you are overlooking a pretty big component of the question...the Group I cation isn't being dissociated into water. We're testing the solubility of the cation when mixed with HCl. And this IS a legitimate question, seeing as our lab manual is the one asking. 

<span>By the way, the answer you're looking for is "Because Group I cations have insoluble chlorides". </span>

<span>"In order...to distinguish cation Group I, one adds HCl to a sample. If a Group I cation is present in the sample, a precipitate will form." </span>
8 0
3 years ago
Why do acids and bases have a good conduction of electricity?
omeli [17]
All acids only conduct electric current when they are dissolved in water, because when they are in an aqueous medium, they undergo ionization, i.e. release <span>ions.</span><span>

HCl --> H</span>⁺ + Cl⁻

The bases also conduct electric current in solution, because the Ionic dissociation sufferers (release the existing ions in the formula) and molecular ionization, suffer the reacting with water and releasing ions.

NaOH ---> Na⁺  + OH⁻

hope this helps!

7 0
2 years ago
. percent iron in a mixture that is 52.2% Fe2O3​
AVprozaik [17]

Answer:

36.51%.

Explanation:

First find the percentage of iron in pure Fe2O3 using the  atomic masses of the elements:

=  (2 * 55.845) * 100 /  (2*55.845+ 3*15.999)

=  69.94 %.

So the percentage of iron in the mixture

=  52.2 * 0.6994

= 36.51 (answer).

8 0
3 years ago
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