Answer:
A star begins its life as a cloud of dust and gas (mainly hydrogen) known as a nebula. A protostar is formed when gravity causes the dust and gas of a nebula to clump together in a process called accretion. ... If a critical temperature in the core of a protostar is reached, then nuclear fusion begins and a star is born.
Explanation:
.
solution:
You need to find the frequency, and they have already given you the wavelength. And since you already know the speed of light, you can use formula (2) to answer this problem. Remember to convert the nano meters to meters because the speed of light is in meters. 
Answer:
pressure
Explanation:
gas convert to liquid at high pressure.
Fission is similar to mitosis because they both involve splitting.
Answer: <span><span>d. mitosis</span></span>
