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spayn [35]
2 years ago
7

What is the atomic number for an element whose mass number is 78,

Chemistry
2 answers:
Ann [662]2 years ago
5 0

Answer:

protons = atomic numbermass number = protons + neutronsatomic number = mass number - neutrons = 78-38 = 40

Explanation:

murzikaleks [220]2 years ago
4 0

Answer:

48

Explanation:

i took the test lolll

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In the laboratory you are asked to make a 0.565 m sodium bromide solution using 315 grams of water. How many grams of sodium bro
Scorpion4ik [409]

Answer : The mass of sodium bromide added should be, 18.3 grams.

Explanation :

Molality : It is defined as the number of moles of solute present in kilograms of solvent.

Formula used :

Molality=\frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Mass of solvent}}

Solute is, NaBr and solvent is, water.

Given:

Molality of NaBr = 0.565 mol/kg

Molar mass of NaBr = 103 g/mole

Mass of water = 315 g

Now put all the given values in the above formula, we get:

0.565mol/kg=\frac{\text{Mass of NaBr}\times 1000}{103g/mole\times 315g}

\text{Mass of NaBr}=18.3g

Thus, the mass of sodium bromide added should be, 18.3 grams.

6 0
3 years ago
What does one mole of oxygen and one mole of carbon dioxide have in common?
arsen [322]

Answer:

Equal number of moles

Explanation:

Thats life

5 0
3 years ago
The base-dissociation constant, kb, for pyridine, c5h5n, is 1.4x10-9 the acid-dissociation constant, ka, for the pyridinium ion,
sp2606 [1]
We are given the base dissociation constant, Kb, for Pyridine (C5H5N) which is 1.4x10^-9. The acid dissociation constant, Ka for the Pyridium ion or the conjugate acid of Pyridine is to be determined. We know from our chemistry classes that:

Kw = Kb * Ka

where Kw is always equal to 1x10^-14

so, to solve for Ka of Pyridium ion, substitute Kb to the equation together with Kw and solve for Ka:

1x10^-14 = 1.4x10^-9 * Ka
solve for Ka

Ka = 7.14x10^-6 

Therefore, the acid dissociation constant of Pyridinium ion is 7.14x10^-6.
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5 0
3 years ago
The sun causes a greenhouse effect on Earth. How is Earth impacted by the greenhouse effect?(1 point)
creativ13 [48]

Answer: Sunlight passes through the atmosphere and warms the Earth's surface. ... As more greenhouse gases are emitted into the atmosphere, heat that would normally be radiated into space is trapped within the Earth's atmosphere, causing the Earth's temperature to increase.

Explanation: This keeps well life on earth so the answer is (3)

:)

4 0
2 years ago
What volume of water must be added
stellarik [79]

Answer:

litre.50000665432158900643212lo

3 0
3 years ago
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