The spectrum of light emitted by helium atoms is different than that emitted by hydrogen atoms becausea. helium is a noble gas, and hydrogen is not. b. helium atoms are more massive, so move more slowly. c. the different atoms have different quantized energy levels. d.the force binding an electron to a helium is larger

Word equation for k(s)+h2o(l) yield koh(aq) + h2(g)

Which of the following is an indication that a substance has undergone a chemical change? a. no new product has been formed. b. the color of the substance has not changed. c. the original constitute has not changed. d. the molecular structure has changed.

Astudent pours 10.0 g of salt into a container of water and observes the amount of time it takes for the salt to dissolve. she then repeats the process using the same amounts of salt and water but this time she slowly stirs the mixture while it is dissolving. the student performs the experiment one more time but this time she stirs the mixture rapidly. the dependent variable in this experiment is: time for salt to dissolve speed of stirring amount of water mass of salt