Vanadium has an atomic mass of 50.9415 amu. It has two common isotopes. One isotope has a mass of 50.9440 amu and a relative abu
1 answer:
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Answer:
Astatine is a halogen with several isotopes that all have short half-lives.
Which of the following combinations of mass number and neutrons are possible as isotopes of astatine? Choose one or more:
i) A = 211, n = 127
ii) A = 210, n = 125
iii) A = 220, n = 134
iv) A = 207, n = 122
v) A = 209, n = 124
Explanation:
The mass number is the sum of the number of protons and the number of neutrons in an atom.
Atomic number of At(astatine ) =85
That means it has --- 85protons.
Its mass number A=210
Hence, the number of neutrons in At are:
Second option:
ii) A=210 , n=125 is the answer.
<h3>Answer:</h3>
1.52 × 10⁻¹⁶ nm
<h3>Explanation:</h3>We are given,
Energy = 3.36 × 10⁻¹⁷ Joules
We are required to find the wavelength of light
We are going to use,
The formula, E = hλ/c
Where E is the energy, λ is the wavelength, h is the plank's constant and c is the speed of light.
h = 6.626 × 10^-34 J-s
c = 2.998 × 10^8 m/s
Working
From the formula;
= (3.36 × 10⁻¹⁷ J)(2.998 × 10^8 m/s) ÷ 6.626 × 10^-34 J-s
= 1.52 × 10⁻²⁵ meters
Therefore, the wavelength in m is 1.52 × 10⁻²⁵ m
Conversion
We need to convert m to nm
Conversion factor is 10⁹
Therefore;
1.52 × 10⁻²⁵ m to nm
will be; 1.52 × 10⁻²⁵ m × 10⁹
= 1.52 × 10⁻¹⁶ nm
Thus, the wavelength in nm is 1.52 × 10⁻¹⁶ nm