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Schach [20]
3 years ago
10

The half-life of oxygen-15 is 124 s. If a sample of oxygen-15 has an activity of 6400 Bq, how many minutes will elapse before it

has an activity of 400 Bq?
Chemistry
1 answer:
NemiM [27]3 years ago
4 0

Answer:

8.27 minutes

Explanation:

Do the half lives first. 6400 Bq->3200 Bq->1600 Bq->800 Bq->400 Bq

The arrows represent one half life therefore there are 4. Next you multiply the 124 second with the 4 half lives. You get 496 second so you would divide that by 60 seconds which will give you 8.27 minutes.

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What was the result of the atomic theory?
Cerrena [4.2K]

Answer:

The result of the atomic theory was atomic theory proposed that all matter was composed of atoms, also postulated that chemical reactions resulted in the rearrangement of the reacting atoms.

4 0
3 years ago
When the equation Sn + HNO₃ → SnO₂ + NO₂ + H₂O is balanced in acidic solution, what is the smallest whole-number coefficient for
balu736 [363]

Answer:

1.

Explanation:

Hello,

In this case, for the given reaction we first assign the oxidation state for each species:

Sn^0 + H^+N^{5+}O^{-2}_3 \rightarrow Sn^{4+}O_2 + N^{4+}O^{2-}_2 + H^+_2O^-

Whereas the half reactions are:

Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow  N^{4+}O^{2-}_2+H_2O

Next, we exchange the transferred electrons:

1\times(Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-)\\\\4\times (H^++H^+N^{5+}O^{-2}_3 +1e^-\rightarrow  N^{4+}O^{2-}_2+H_2O)\\\\\\Sn^0+2H_2O \rightarrow Sn^{4+}O_2 +4H^++4e^-\\\\4H^++4H^+N^{5+}O^{-2}_3 +4e^-\rightarrow  4N^{4+}O^{2-}_2+4H_2O

Afterwards, we add them to obtain:

Sn^0+2H_2O+4H^++4H^+N^{5+}O^{-2}_3  \rightarrow Sn^{4+}O_2 +4H^++4N^{4+}O^{2-}_2+4H_2O

By adding and subtracting common terms we obtain:

Sn^0+4H^+N^{5+}O^{-2}_3  \rightarrow Sn^{4+}O_2 +4N^{4+}O^{2-}_2+2H_2O

Finally, by removing the oxidation states we have:

Sn + 4HNO_3 \rightarrow SnO_2 + 4NO_2 + 2H_2O

Therefore, the smallest whole-number coefficient for Sn is 1.

Regards.

6 0
3 years ago
What is the total number of protons in an atom with the electron configuration 2-8-18-32-18-1.
svp [43]

The total number of protons in this atom is 79 because an atomic number of an element is equal to the number of protons. Here, the atomic number is 79 after adding the given electronic configuration.

What are Protons?

Every atom has a proton, a subatomic particle, in its nucleus. The particle possesses an electrical charge that is positive and opposite to the electrons.

What is Atom?

A nucleus plus one or more electrons bound to the nucleus make up an atom. The quantity of protons or electrons in an element's atom determines how different it is from other similar elements. The atomic number of an element, which serves as its primary identification, is the sum of its protons or electrons.

What is Electronic configuration?

The arrangement of electrons in atomic or molecular orbitals within an atom, molecule, or other physical structure is known as the electron configuration.

Hence, the total number of protons in this atom is 79, after adding 2 + 8 + 18 + 32 + 18 + 1.

To know more about Atom, check out:

brainly.com/question/6258301

#SPJ4

5 0
1 year ago
Wet snow is best for snow man building<br>​
fredd [130]

Answer:

<h2>Hope my answer helps</h2>

Explanation:

<h2>Moist to wet snow is the ideal moisture content needed to build the best snowman. If the snow is too dry, it is comparable to loose powder and in turn, the snow won't stick together. On the other hand, if the snow has too much moisture and is slushy, it can't form into a solid.</h2>
4 0
3 years ago
What is NaOH in science ​
xz_007 [3.2K]

Answer: Sodium hydroxide

7 0
3 years ago
Read 2 more answers
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