<u>Answer:</u> The mass defect for the formation of phosphorus-31 is 0.27399
<u>Explanation:</u>
Mass defect is defined as the difference in the mass of an isotope and its mass number.
The equation used to calculate mass defect follows:
![\Delta m=[(n_p\times m_p)+(n_n\times m_n)]-M](https://tex.z-dn.net/?f=%5CDelta%20m%3D%5B%28n_p%5Ctimes%20m_p%29%2B%28n_n%5Ctimes%20m_n%29%5D-M)
where,
= number of protons
= mass of one proton
= number of neutrons
= mass of one neutron
M = mass number of element
We are given:
An isotope of phosphorus which is 
Number of protons = atomic number = 15
Number of neutrons = Mass number - atomic number = 31 - 15 = 16
Mass of proton = 1.00728 amu
Mass of neutron = 1.00866 amu
Mass number of phosphorus = 30.973765 amu
Putting values in above equation, we get:
![\Delta m=[(15\times 1.00728)+(16\times 1.00866)]-30.973765\\\\\Delta m=0.27399](https://tex.z-dn.net/?f=%5CDelta%20m%3D%5B%2815%5Ctimes%201.00728%29%2B%2816%5Ctimes%201.00866%29%5D-30.973765%5C%5C%5C%5C%5CDelta%20m%3D0.27399)
Hence, the mass defect for the formation of phosphorus-31 is 0.27399
Answer:
Group 1
Explanation: because the compound has a formula of M2O , the number of valence electrons of M should be 1.
Answer is none of the above
The right answer is screening test.
In medicine, screening consists of looking for one or more diseases or abnormalities known as "at risk" in individuals of a given population.
These investigations are followed or not by medical consultations, clinical examinations and treatments.
In addition, screening is a preliminary procedure (test or examination) to detect one or more characteristic signs or symptoms of a disease or syndrome and potentially leading to further investigation.
Answer:
1.2*10^24 molecules of CF4
Explanation:
the molar mass of cf4 is 88.0043 g/mol
176/88.0043 = 2 moles of CF4
Then multiply by avogadro's number (6.022*10^23) to get the number of molecules
2*6.022*10^23 = 1.2*10^24 molecules of CF4
