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Lilit [14]
2 years ago
6

Which electron configuration represents a selenium atom in an excited state?(1) 2-7-18-6(2) 2-7-18-7(3) 2-8-18-6(4) 2-8-18-7

Chemistry
1 answer:
rosijanka [135]2 years ago
5 0
(2) 2 - 7 - 18 - 7 does, because the electron from the L shell jumped to the N shell, which requires energy.

The rest of them are either different types of atoms (different elements) or are not the excited state (ground state)
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A solution of ammonia and water contains 2.10×1025 water molecules and 7.10×1024 ammonia molecules. How many total hydrogen atom
Natali5045456 [20]

There are 6.33 × 10²⁵ hydrogen atoms in this solution in total.

<h3>Explanation</h3>
  • There are two hydrogen atoms in each water \text{H}_2\text{O} molecule.
  • There are three hydrogen atoms in each ammonia \text{NH}_3 molecule.

2.10 × 10²⁵ water molecules and 7.10 × 10²⁴ ammonia molecules will contain

2 \times 2.10 \times 10^{25} + 3 \times 7.10 \times 10^{24} = 6.33 \times 10^{25} hydrogen atoms in total.

8 0
3 years ago
Tin (II) fluoride, formerly found in many kinds of toothpaste, is formed in this reaction: Sn (s) + 2HF (g) ——&gt; SnF2 (s) + H2
Readme [11.4K]

1.34 L of HF

Explanation:

We have the following chemical reaction:

Sn (s) + 2 HF (g) → SnF₂ (s) + H₂ (g)

First we calculate the number of moles of SnF₂:

number of moles = mass / molecular weight

number of moles of SnF₂ = 5 / 157 = 0.03 moles

From the chemical reaction we see that 1 mole of SnF₂ are produced from 2 moles of SnF₂. This will mean that 0.03 moles of SnF₂ are produced from 0.06 moles of HF.

Now at standard temperature and pressure (STP) we can use the following formula to calculate the volume of HF:

number of moles = volume / 22.4 (L/mole)

volume of HF = number of moles × 22.4

volume of HF = 0.06 × 22.4 = 1.34 L

Learn more about:

problems with gases at STP

brainly.com/question/8857334

#learnwithBrainly

8 0
3 years ago
PLEASE ANSWER
lisov135 [29]

Answer:

B.

Explanation:

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What will increased temperature in a reaction cause
uranmaximum [27]
I think your answer is 2 because the temperature will rise so the particles will move faster
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Rashid [163]

Answer:

true

Explanation:

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