Answer:19. He says that he’s been really tired since several weeks ago. 20. A friend of us is going to pick us up at the airport. 21. I’ve worked like a waiter in the past, but I wouldn’t want to do it again. 22
Explanation:
Answer:
The mass of the element is 26.20 amu
Explanation:
In this question, we are asked to calculate the mass of an element with 15 protons, 13 electrons and 11 neutrons
To calculate the atomic mass of the element, we take into consideration the masses of the individual sub atomic particles
Electrons have 0 atomic mass unit(their masses are negligible) we have no business here, Protons have a mass of
1.00727647 amu, while the mass of neutron is 1.0086654 amu
The mass of 15 protons is thus 15 * 1.00727647 = 15.10914705 amu
The mass of 11 neutrons is 11 * 1.0086654 =
11.0953194 amu
Adding this together, we have ; 11.0953194 + 15.10914705 = approximately 26.20 amu
☃️ Chemical formulae ➝ 
How to find?
For solving this question, We need to know how to find moles of solution or any substance if a certain weight is given.
Solution:
❍ Molecular weight of
= 2 × 126.90
= 253.80
= 254 (approx.)
❍ Given weight: 12.7
Then, no. of moles,
⇛ No. of moles = 12.7 / 254
⇛ No. of moles = 0.05 moles
⚘ No. of moles of Iodine molecule in the given weight = <u>0.05</u><u> </u><u>moles </u>
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