Which diagram is the best model for a solid? Substance C Substance A Substance B

PLEASE HELP!!! The gold foil Rutherford used in his scattering experiment had a thickness of approximately 4×10−3 mm . If a sing

Ilya [14]

Answer:

16 atoms thick

Explanation:

4*10-3= 37

2.9*10-8=21

37-21=16

3 0

3 years ago

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A certain first-order reaction (A→products) has a rate constant of 7.20×10−3 s−1 at 45 ∘C. How many minutes does it take for the

lesya692 [45]

Answer:

6,41 min

Explanation:

For the reaction:

A → products

kinetics first-order reaction law is:

ln[A] = ln[A]₀ -kt

Where [A] is concentration of reactant, [A]₀ is initital concentration of reactant, k is rate constant and t is time.

If the concentration of A is 6,25% you can assume:

[A] = 6,25; [A]₀= 100. Replacing:

ln(6,25) = ln(100) -7,20×10⁻³s⁻¹t

-2,7726 = -7,20×10⁻³s⁻¹t

385s = t

In minutes:

385s× $\frac{1min}{60s}$ = <em>6,41 min</em>

I hope it helps!

6 0

3 years ago

During a routine check of the fluoride content of Gotham City\'s water supply, the following results were obtained from replicat

Aleksandr-060686 [28]

Answer:

The mean is $x=0.503\frac{mg}{L}$

The 90% confidence interval is:

$i_{0.90}=[0.492\frac{mg}{L},0.514\frac{mg}{L}]$

Explanation:

1. First organize the data:

$x_{1}=0.487$

$x_{2}=0.487$

$x_{3}=0.511$

$x_{4}=0.511$

$x_{5}=0.519$

As there are 5 data, the sample size (n) is n=5

2. Calculate the mean x:

The mean is calculated adding up all the data and divide them between the sample size.

$x=\frac{0.511+0.487+0.511+0.487+0.519}{5}$

$x=0.503\frac{mg}{L}$

3. Find 90% confidence interval.

The formula to find the confidence interval is:

$i_{0.90}=[x+/-z_{\frac{\alpha}{2}}*(\frac{d}{\sqrt{n}})]$ (Eq.1)

where x is the mean, d is the standard deviation and n is the sample size.

And

$1-\alpha=0.90$

$\alpha=0.10$

$\frac{\alpha}{2}=0.05$

$z_{0.05}=1.645$

4. Find the standard deviation

$d=\sqrt{\frac{(x_{1}-x)^{2}+(x_{2}-x)^{2}+(x_{3}-x)^{2}+(x_{4}-x)^{2}+(x_{5}-x)^{2}}{n-1}}$

$d=\sqrt{\frac{(0.487-0.503)^{2}+(0.487-0.503)^{2}+(0.511-0.503)^{2}+(0.511-0.503)^{2}+(0.519-0.503)^{2}}{4}}$

$d=\sqrt{\frac{(-0.016)^{2}+(-0.016)^{2}+(0.008)^{2}+(0.008)^{2}+(0.016)^{2}}{4}}$

$d=\sqrt{2.24*10^{-4}}$

$d=0.015$

5. Replace values in (Eq.1):

$i_{0.90}=[0.503+/-1.645*(\frac{0.015}{2.236})]$

For the addition:

$i_{0.90}=[0.503+1.645*(\frac{0.015}{2.236})]$

$i_{0.90}=0.514$

For the subtraction:

$i_{0.90}=[0.503-1.645*(\frac{0.015}{2.236})]$

$i_{0.90}=0.492$

The 90% confidence interval is:

$i_{0.90}=[0.492,0.514]$

4 0

3 years ago

About 25 of the 92 natural elements are known to be essential to life. which four of these 25 elements make up approximately 96%

ikadub [295]

The correct answer would be the second option. Four of these 25 elements that make up approximately 96% of living matter are carbon, hydrogen, nitrogen, oxygen. The elements carbon and hydrogen are the backbone for organic compounds which is the foundation of cells that are present in all living matter. Also, the cells in all living matter are made up of protein which are primarily made up of amino acids which contains nitrogen, oxygen, carbon and hydrogen atoms. So, basically, without these elements in the cells all living matter would not be present and there would be no life in any case.

6 0

3 years ago

What is the formula of the ion formed when sodium achieves a stable electron configuration?

artcher [175]

Sodium is a group 1 element, so it forms a cation with a +1 charge by losing one electron, so it will become Na+

3 0

4 years ago