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vredina [299]
3 years ago
12

A sample can not be broken down physically or chemically what is it

Chemistry
2 answers:
KIM [24]3 years ago
6 0

Answer:

Pure Substance. A sample of matter, either a single element or a single compound, that has definite chemical and physical properties. Element. A pure substance that cannot be broken down into other substances by chemical or physical means.

Explanation:

Sorry if it's wrong!!!!!!!

uysha [10]3 years ago
4 0

Answer:

Elements

Explanation:

Elements cannot be broken down into anything simpler physically or chemically. Compounds: are pure substances that are made up of more than l type of atom and can be broken down or decomposed into its individual elements by chemical methods, but cannot be separated by physical methods.

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Check the statements that are accurate. Check all of the boxes that apply. Before Thomson’s experiments, scientists accepted tha
elixir [45]
Answer 1) It is incorrect.

Explanation : For the statement; 

Thomson did experiments with cathode ray tubes  to show that all atoms contain tiny negatively charged subatomic particles called as electrons<span>.

So the statement should be like this:
AFTER the </span><span>Thomson’s experiments, scientists accepted that the atom was made up of smaller particles.

Answer 2) This is correct.

Explanation : Rutherford was the scientist who discovered that atoms has volume is because of the empty spaces inside it. He did the gold foil experiments to prove this and he was successful in doing this by concluding that tiny dense empty places are occupied by positively charged nucleus.

Answer 3) This is Correct.

Explanation : After Thomson and Rutherford, Millikan also performed an experiment to prove that an atom contains a small positively charged nucleus which is usually surrounded by negatively charged electrons by his oil drop experiment.</span>
5 0
4 years ago
How many atoms of sodium are in 3.80 mol of sodium, Na?
vova2212 [387]

Answer:

2.29 × 10²⁴ atoms Na

Explanation:

Step 1: Define

Avagadro's Number: 6.02 × 10²³ atoms, molecules, formula units, etc.

Step 2: Stoichiometry

3.80 \hspace{3} mol \hspace{3} Na(\frac{6.02(10)^{23} \hspace{3} atoms \hspace{3} Na}{1 \hspace{3} mol \hspace{3} Na} ) = 2.2876 × 10²⁴ atoms Na

Step 3: Simplify

We have 3 sig figs.

2.2876 × 10²⁴ atoms Na ≈ 2.29 × 10²⁴ atoms Na

3 0
4 years ago
Determine the energy of the electron in the 1s orbital of a helium ion (He+ )
Luda [366]
He Rydberg formula can be extended for use with any hydrogen-like chemical elements. 
<span>1/ λ = R*Z^2 [ 1/n1^2 - 1/n2^2] </span>
<span>where </span>
<span>λ is the wavelength of the light emitted in vacuum; </span>
<span>R is the Rydberg constant for this element; R 1.09737x 10^7 m-1 </span>
<span>Z is the atomic number, for He, Z =2; </span>
<span>n1 and n2 are integers such that n1 < n2 </span>
<span>The energy of a He+ 1s orbital is the opposite to the energy needed to ionize the electron that is </span>
<span>taking it from n = 1 (1/n1^2 =1) to n2 = ∞ (1/n2^2 = 0) </span>
<span>.: 1/ λ = R*Z^2 = 1.09737x 10^7*(2)^2 </span>
<span>λ = 2.278*10^-8 m </span>
<span>E = h*c/λ </span>
<span>Planck constant h = 6.626x10^-34 J s </span>
<span>c = speed of light = 2.998 x 10^8 m s-1 </span>
<span>E = (6.626x10^-34*2.998 x 10^8)/(2.278*10^-8) = 8.72*10^-18 J ion-1 </span>
<span>Can convert this value to kJ mol-1: </span>
<span>(8.72*10^-18*6.022 x 10^23)/1*10^3 = 5251 kJ mol-1 </span>
<span>Lit value: RP’s secret book: 5240.4 kJ mol-1 (difference is due to a small change in R going from H to He+) </span>
<span>So energy of the 1s e- in He+ = -5251 kJ mol-1</span>
6 0
3 years ago
A 50 W engine generates 50 J of energy. How long did it run for?
Inessa [10]
The engine ran for 10 second
6 0
3 years ago
Read 2 more answers
What is the percent by mass of magnesium sulfate in MgSO4 · 7H2O?
AfilCa [17]
ANSWER - 48.83%

Mg - 24.31
S - 32.07
O - 16x4 - 64
ADD ALL TOGETHER = 120.38

H - 1.01x2 - 2.02
O - 16
TOTAL = 18.02x7 = 126.14

ADD 120.38 to 126.14 = 246.52
last part divide MgSO4 by total compound mass 
120.38/246.52 then multiply by 100 = 48.831
7 0
3 years ago
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