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Lesechka [4]
3 years ago
8

NEED HELP ASAPPP What is the number of beryllium atoms in 78.0g of Be?

Chemistry
1 answer:
polet [3.4K]3 years ago
4 0

Answer: number of atoms is 5.21 · 10^24

Explanation: Atomic mass of Be is 9.012 g/mol.

Number of moles n = m/M = 78.0 g / 9.012 g/mol =

Multiply this with Avogadro number Na = 6.022*10^23 1/mol

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A(n) _______ is a substance of two or more atoms held together with chemical bonds.
sergejj [24]
It is called a molecule
3 0
3 years ago
(ii) Electrons are supplied to the external circuit. How and where is this done?<br> [2]
pentagon [3]

Answer:

The electrons are supplied by the species getting oxidized. They move from anode to the cathode in the external circuit. The external battery supplies the electrons. They enter through the cathode and come out through the anode

7 0
3 years ago
What happens when stress builds at faults? Select three options
Stels [109]

Answer:

When Stress builds up at faults, the 3 options that are correct and can happen

- Rock can bend and break;

- Earthquakes develop at Earth's surface

- Forces affect Earth's rocks

Explanation:

This is a Geography question

- Rock can bend and break

When Stress builds up at faults, it leads to a geologic activity that causes a lot of pressure that lead to the movement of the earth's crust. The movement creates such intense pressure on the rocks, that, with time, they twist, bend, and break due to this pressure.

- Earthquakes develop at Earth's surface

As explained earlier, this intense pressure can lead to rocks breaking, as these rocks break inside the earth's crust, the gaps that come into play after the breaking of the rocks causes the remaining rocks to adjust, releasing a lot of force, and subsequently creating earthquakes.

- Forces affect Earth's rocks

As explained earlier, the forces resulting from these intense pressures, affect the earth's rocks. They move them both vertically and horizontally, change their shape and eventually break them.

Hope this Helps!!!

8 0
3 years ago
Two colorless solutions are mixed together bubbles form as the solution is stirred give to possible explanations for this result
Aleks [24]
One possible answer could be that a chemical reaction has occurred.
5 0
2 years ago
<img src="https://tex.z-dn.net/?f=H_2PO_4%5E-%28aq%29%20%5Crightarrow%20H%5E%2B%28aq%29%20%2B%20HPO_4%5E%7B2-%7D%28aq%29" id="Te
klasskru [66]

Answer:

The pH of the buffer solution = 8.05

Explanation:

Using the Henderson - Hasselbalch equation;

pH = pKa₂ + log ( [HPO₄²-]/[H₂PO4⁻]

where pKa₂ = -log (Ka₂) = -log ( 6.1 * 10⁻⁸) = 7.21

Concentration of OH⁻ added = 0.069 M (i.e. 0.069 mol/L)

[H₂PO4⁻] after addition of OH⁻ = 0.165 - 0.069 = 0.096 M

[HPO₄²-] after addition of OH⁻ = 0.594 + 0.069 = 0.663 M

Therefore,

pH = 7.21 + log (0.663 / 0.096)

pH = 7.21 + 0.84

pH = 8.05

4 0
3 years ago
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