Astudent places a beaker on a hot plate. to the beaker, he adds a clear liquid and a white powder. the mixture instantly begins to bubble. he concludes that a chemical reaction has occurred. do you agree with his conclusion? why or why not? explain.

True, because if it wasn't a chemical reaction it would have proceeded to stay the same. but it begins to bubble.
sorry if this isn't the best answer I'm trying my best.

Where is the graph ?

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.