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2 years ago

) Experimental evidence indicates that the nucleus of an atom

Chemistry

1 answer:

geniusboy [140]2 years ago

5 0

Answer:

A (contains most of the mass of the atom)

Evidence has it that a proton is about 2000 times as massive as an electron.

And there is usually multiple protons and neutrons in the nucleus

From what I just said, you can say that B is wrong

C however is also wrong because protons have a +charge and neutrons are neutrle which means you always have a charge > (greater than) 0

And D is wrong because electrons (which are not in the nucleus) have a neg charge. and protons have a + charge and are in the nucleus

So your answer is A

Hope it helped

Spiky Bob

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"A group of college students believes that herbal tea has remarkable restorative powers. To test their belief, they visit a loca

Georgia [21]

D) the college students

Explanation:

In the experiment conducted by staffs of the nursing home, the group of college students that came for the experiment are the subjects of the experiment. A subject is a person that participates in a research.

In this research, the college students are the human participants in the experiment.
There must be a mutual agreement between the researcher and the subject because the subject is one that is being tested to see an outcome.
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2 years ago

Look at the model below. Which formula is best represented by this model?

Olenka [21]

The third answer because there are two of each atom

6 0

3 years ago

Write the number in scientific nation form

Yuri [45]

Answer:

its already in scientific notation form however its ordinary or real form is -0.005682

Explanation:

scientific notation

when a number is expressed with some power of 10 multiplied by a number between 1 to 10 is called scientific notation

4 0

3 years ago

When calcium carbonate is added to hydrochloric acid, calcium chloride, carbon dioxide, and water are produced.

sp2606 [1]

Answer:

Mass of CaCl₂ = 20 g

CaCO is presewnt in excess.

Mass of of CaCO₃ remain unreacted = 7.007 g

Explanation:

Given data:

Mass of calcium carbonate = 25 g

Mass of hydrochloric acid = 13.0 g

Mass of calcium chloride produced = ?

Chemical equation:

CaCO₃ + 2HCl → CaCl₂ + H₂O + CO₂

Number of moles of CaCO₃:

Number of moles of CaCO₃ = Mass /molar mass

Number of moles of CaCO₃= 25.0 g / 100.1 g/mol

Number of moles of CaCO₃ = 0.25 mol

Number of moles of HCl:

Number of moles of HCl = Mass /molar mass

Number of moles of HCl = 13.0 g / 36.5 g/mol

Number of moles of HCl = 0.36 mol

Now we will compare the moles of CaCl₂ with HCl and CaCO₃ .

CaCO₃ : CaCl₂

1 : 1

0.25 : 0.25

HCl : CaCl₂

2 : 1

0.36 : 1/2 × 0.36 = 0.18 mol

The number of moles of CaCl₂ produced by HCl are less it will be limiting reactant.

Mass of CaCl₂ = moles × molar mass

Mass of CaCl₂ =0.18 mol × 110.98 g/mol

Mass of CaCl₂ = 20 g

The calcium carbonate is present in excess.

HCl : CaCO₃

2 : 1

0.36 : 1/2 × 0.36 = 0.18 mol

So, 0.18 moles react with 0.36 moles of HCl.

The moles of CaCO₃ remain unreacted = 0.25 -0.18

The moles of CaCO₃ remain unreacted = 0.07 mol

Mass of of CaCO₃ remain unreacted = Moles × molar mass

Mass of of CaCO₃ remain unreacted = 0.07 mol × 100.1 g/mol

Mass of of CaCO₃ remain unreacted = 7.007 g

7 0

3 years ago

What is the identity of the element, and how many neutrons does it have? An elements most stable ion forms an ionic compound wit

Pani-rosa [81]

Answer:

B. CA, 14

Explanation:

Atoms of elements contain small particles known as electrons, neutrons, and protons. The nucleus of an atom is made up of neutrons and protons which are at the center of the atom. Electrons on the other hand surrounds the nucleus. Electron has negative charge while proton has a positive charge. The number of neutrons is equivalent to the number of protons . In addition, the number of protons is equal to mass number minus the number of electrons.

For the compound $XCl_{2}$ , it can be broken down into $X^{2+}$ and $2Cl^{-}$ . Its ion has a mass of 34 and 18 electrons which means it has already lost 2 electrons.

Therefore:

For the given element, the number of electrons is 18+2 = 20 electrons.

The number of protons = 34 - 20 = 14.

And the number of neutrons is 14.

Only option B has the correct answer.

6 0

3 years ago