Where are the answers? If there's anything about a white light coming from space I would choose that one.
The presence of helium gas indicates the radioactive sample is most likely decaying by α-decay, or alpha decay. α-decay is the type of radioactive decay in which an atomic nucleus emits α particles. α particles are Helium nuclei. So the correct answer would be α-decay.
Answer:
Hits per second=199 hit/s
Explanation:
#Given the angular velocity, 
, radius of the record 
and the distance between any two successive bumps on the groove as 
.
The linear speed of the record in meters per second is:
#From 
above, if the bumps are uniformly separated by 1m, then the rate at which they hit the stylus is:
Hence the bumps hit the stylus at around 199hit/s
