Where are the instructions that tell the cell everything it needs to survive?

The element boron exists in nature as two isotopes: 10B has a mass of 10.0129 u, and 11B has a mass of 11.0093 u. The average at

Shalnov [3]

Answer:

Percentage abundance of B 10 is = 20 %

Percentage abundance of B 11 is = 80 %

Explanation:

The formula for the calculation of the average atomic mass is:

$Average\ atomic\ mass=(\frac {\%\ of\ the\ first\ isotope}{100}\times {Mass\ of\ the\ first\ isotope})+(\frac {\%\ of\ the\ second\ isotope}{100}\times {Mass\ of\ the\ second\ isotope})$

Given that:

Since the element has only 2 isotopes, so the let the percentage of first be x and the second is 100 -x.

For first isotope, B 10:

% = x %

Mass = 10.0129 u

For second isotope, B 11:

% = 100 - x

Mass = 11.0093 u

Given, Average Mass = 10.81 u

Thus,

$10.81=\frac{x}{100}\times {10.0129}+\frac{100-x}{100}\times {11.0093}$

$10.0129x+11.0093\left(100-x\right)=1081$

Solving for x, we get that:

x = 20 %

Thus percentage abundance of B 10 is = 20 %

Percentage abundance of B 11 is = 100 - 20 % = 80 %

8 0

3 years ago

Read 2 more answers

Where are the different particles in an atom located and what are their charges?

satela [25.4K]

Explanation:

The different subatomic particles in an atom are the:

Protons which are the positively charged particles.
Electrons which are the negatively charged particles.
Neutrons which do not carry any charges.

Protons and neutrons are located in the nucleus of an atom which is the tiny center of the atom.

Electrons orbits around the nucleus and fill the rest of the volume of atom.

4 0

3 years ago

Braddy connected the lose wire to the battery and created an electromagnet. He picked up 45 thumb tacks with his electromagnet,

Usimov [2.4K]

In order to increase the strength of his electromagnet and pick up more thumbtacks Braddy should use two batteries instead of one. Using two batteries will increase the amount of current in the coils which will induce a higher electromagnetic field in the nail.
Another option would be to increase the number of coils of wire.

4 0

4 years ago

Read 2 more answers

How many atoms of each element are in each element represented in 3 Fe(OH)2

Svetlanka [38]

Fe - 3
O - 6
H - 6
-----------------------

7 0

4 years ago

4. Your mission, if you choose to accept it, is to make 10mmol/L acetate buffer, pH5.0. Beginning with 10mmol/L HAc, what concen

julia-pushkina [17]

Answer:

6,45mmol/L of NaOH you need to add to reach this pH.

Explanation:

CH₃COOH ⇄ CH₃COO⁻ + H⁺ pka = 4,74

Henderson-Hasselbalch equation for acetate buffer is:

5,0 = 4,74 + log₁₀ $\frac{[CH_{3}COO^-]}{[CH_{3}COOH]}$

Solving:

1,82 = $\frac{[CH_{3}COO^-]}{[CH_{3}COOH]}$ (1)

As total concentration of acetate buffer is:

10 mM = [CH₃COOH] + [CH₃COO⁻] (2)

Replacing (2) in (1)

[CH₃COOH] = 3,55 mM

And

[CH₃COO⁻] = 6,45 mM

Knowing that:

CH₃COOH + NaOH → CH₃COO⁻ + Na⁺ + H₂O

Having in the first 10mmol/L of CH₃COOH, you need to add 6,45 mmol/L of NaOH. to obtain in the last 6,45mmol/L of CH₃COO⁻ and 3,55mmol/L of CH₃COOH .

I hope it helps!

7 0

3 years ago