Answer:
2.16 x 10^7 years
Explanation:
R = 6.9 x 10^20 m
ω = 9.2 x 10^-15 rad/s
T = 2π / ω
T = ( 2 x 3.14 ) / ( 9.2 x 10^-15)
T = 6.826 x 10^14 second
T = 2.16 x 10^7 years
Answer:
B AND D
HOPE ITS HELF FUL .........
The atomic number Z of an element is the number of protons it contains (and in an atom it is equal to the number of electrons). The mass number M is close to the mass of one mol of the substance but it is defined as the number of protons and neutrons in the nucleus of the atom; there, the main mass of the atom is contained. Hence, N=M-Z=74-36=38(since M counts both protons and neutrons while Z only protons). Thus, it has 38 neutrons.
