Which of the following best describes why the atomic model has changed repeatedly over the past 200 years? 1. most of the models were huge mistakes. 2. very few people thought the models were valid. 3. the models were known to be incomplete and needed to be fixed. 4. the results of further experimentation to revise and improve the model.

answer

fusion: the energy source of stars. the energy released from the collapse of the gas into a protostar causes the center of the protostar to become extremely hot. when the core is hot enough, nuclear fusion commences. fusion is the process where two hydrogen atoms combine to form a helium atom, releasing energy.

hope it

c. heat could easily travel through the molecules in the air and escape/enter the flask. removing the air slows down the heat transfer.  

i believe it is-

d.) gravity pulled particles of dust and gas together to form planets.