An atom of boron has an atomic number of 5 and an atomic mass of 11. the atom contains
5 protons, 6 electrons, and 5 neutrons.
11 protons, 11 electrons, and 5 neutrons.
5 protons, 5 electrons, and 6 neutrons.
11 protons, 6 electrons, and 6 neutrons.

It is C.

Explanation:

The atomic mass = number  of protons + number of neutrons

= 5 + 6 = 11. The number of protons = the number of electrons.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.