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3 years ago

an atom has 79 protons, 78 electrons and a mass number of 118. how many neutrons does this atom have

Chemistry

1 answer:

igomit [66]3 years ago

4 0

Answer:

Explanation:

Electrons weigh almost nothing, so their mass doesn't really matter for these types of problems. Just subtract 118-79 to find the remaining mass which is for the neutrons.

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Please help me for question 1 and 2

likoan [24]

Answer:-

1) 6 mol

2) Mo

Explanation: -

Mass of Ozone = 48 g

Chemical formula of ozone = O3

Molar mass of Ozone O 3 = 16 x 3 = 48 g mol-1

Number of moles of ozone = Mass / molar mass

= 48 g / 48 g mol-1

= 1 mol

According to Avogadro’s law, 1 mole of a substance has 6.02 x 10^ 22 molecules.

So 1 mol of O3 has 6.02 x 10^ 22 molecules of ozone.

Now each Ozone molecule has 3 atoms of oxygen.

So, 1 mol of ozone has 3 x 6.02 x 10^22 atoms of oxygen.

Sodium must have 2 x 3 x 6.02 x 10^22 atoms as per the question.

According to Avogadro’s law, 6.02 x 10^ 22 atoms are in 1 mol of sodium

So, for 2 x 3 x 6.02 x 10^22 atoms, there should be (1/ 6.02 x 10^ 22) x 2 x 3 x 6.02 x 10^22

= 6 mol of sodium.

Let the mass of M be m g

Formula of hexafluoride = MF6.

Mass of the hexafluoride = g + 6 x 19

= m + 114

Mass of M=0.250g

Moles of M = 0.250/m

Mass of MF6= 0.547g

Moles of MF6 = 0.547/ (m + 114)

We know 1 mole of M gives 1 mole of MF6.

0.250/m moles of M gives 0.250/m moles of MF6.

But number of moles of MF6 = 0.547/ (m + 114)

Thus

0.250/m = (0.547)/ (m +114))

0.250m + 0.250 x 114 = 0.547m

m = 0.250 x 114 / (0.547 -0.250)

= 96

We see from the given data that Mo is 96.

So M is Mo.

4 0

3 years ago

Why are baking directions on cake mix boxes different for higher altitudes

Blababa [14]

Answer:

Explanation:First, the dry air at high elevations tends to make things dry out quickly. Second, the boiling point of water is lower at altitude, which means that moisture will tend to bake out of your cakes more quickly. ... In the reduced air pressure of high altitudes, your leavening ingredients will act more powerfully.

7 0

3 years ago

Your friend challenged you to a race you know in order to beat him you must run 15 meters within 20 seconds in the northern dire

Marat540 [252]

Answer:

.75 meter north

Explanation:

v = d/t

v = 15/20

v = .75

7 0

3 years ago

For below checmical equation (which may or may not be balanced), list the number of each type of atom on each side of the equati

Olegator [25]

Answer:

Left hand side:-

Carbon - 12

HYdrogen - 28

Oxygen - 38

Right hand side:-

Carbon - 12

Hydrogen - 28

Oxygen - 38

Since, the number of atoms each side are equal, the reaction is balanced.

Explanation:

The given reaction is:-

$2C_6H_{14}_{(l)}+19O_2_{(g)}\rightarrow 12CO_2_{(g)}+14H_2O_{(g)}$

Left hand side:-

Carbon - 12

HYdrogen - 28

Oxygen - 38

Right hand side:-

Carbon - 12

Hydrogen - 28

Oxygen - 38

<u>Since, the number of atoms each side are equal, the reaction is balanced.</u>

5 0

3 years ago

Consider the heating curve for water. A graph of the heating curve for water has time in minutes on the horizontal axis and Temp

Zolol [24]

Answer:

0°C.

Explanation:

Hello,

In this case, given the heating curve of water on the attached document, we can notice that at 0 °C the solid starts melting, which means that the melting point is reached. Melting point is known as a physical change whereby a solid changes to liquid by the addition of heat as it allows the molecules to separate to each other.

Best regards.

4 0

3 years ago

an atom has 79 protons, 78 electrons and a mass number of 118. how many neutrons does this atom have​

an atom has 79 protons, 78 electrons and a mass number of 118. how many neutrons does this atom have