Question

1u is equal to

• A. 931.48 MeV
• B. 1.67 kg
• C. th mass of
• D. 1 dalton

Answer 1

Answer: (A), (B), (C), (D)

The correct options are
A

931.48 MeV

B

1.67 kg

C

th mass of

D

1 dalton

From definition of Atomic mass unit(amu).
1 amu = 1 dalton
Now a days, 1 amu = 1u
Since ¹²C is used as reference for atom weight,
1u = $\frac{1}{12}$ th the mass of one ${}^{12}C$ atom.
So, as of now, b, c and d are correct.
But, a is a unit of energy and u is a unit of mass.
So, to connect mass and energy, we use Einstein's relation E = m$c^2$
1u = 1.66 $\times$ ${10}^{-27}$ kg
E = m$c^2$
= 1.66 $\times$ ${10}^{-27}$ $\times$ ${(3\times {10}^8)}^2$
The unit MeV is ${10}^6$ eV
eV is a unit of energy