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arsen [322]
3 years ago
10

An atom of 40 18 Ar has a nucleus that contains a total of

Chemistry
2 answers:
melisa1 [442]3 years ago
5 0
Atoms are composed of protons, electrons, and neutrons. so, answer D can be discarded because it is not what atoms are made of. 

40 and 18 represent the atomic mass and atomic number respectively. the atomic number presents the number of protons. so there are 18 protons. the number of neutrons can be determined by taking the atomic mass minus the atomic number. neutrons= 40-18= 22 neutrons.

so the answer is B

Answer A may be correct if we assume the atom is neutral. in a neutral atom, the number of protons is the same as the number of electrons. but the electrons are not in the nucleus but orbiting it. the question specified the nucleus.
Cloud [144]3 years ago
4 0
The correct answer is b, 18 protons
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3 years ago
Which ionic compound is soluble in water pbbr2, fe (oh)3,ca(no3)2, baso4?
Anton [14]

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5 0
3 years ago
Which reaction follows the law of conservation of matter?
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6 0
3 years ago
Starting from a 1 M stock of NaCl, how will you make 50 ml of 0.15 M NaCl?
WARRIOR [948]

Answer:

We need 7.5 mL of the 1M stock of NaCl

Explanation:

Data given:

Stock = 1M this means 1 mol/ L

A 0.15 M solution of 50 mL has 0.0075 moles NaCl per 50 mL

Step 2: Calculate the volume of stock we need

The moles of solute will be constant

and n = M*V  

M1*V1 = M2*V2

⇒ with M1 = the initial molair concentration = 1M

⇒ with V1 = the volume we need of the stock

⇒ with V2 = the volume we want to make of the new solution = 50 mL = 0.05 L

⇒ with M2 = the concentration of the new solution = 0.15 M

1*V1 = 0.15*(50)

V1 = 7.5 mL

Since 0.0075 L of 1M solution contains 0.0075 moles

50 mL solution will contain also 0.0075 moles but will have a molair concentration of 0.0075 moles / 0.05 L =0.15 M

We need 7.5 mL of the 1M stock of NaCl

6 0
3 years ago
Which equation is balanced?
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Answer:

A I think

Explanation:

im not sure so do with that what you will

8 0
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