3. the chemical equation for what happened to the zinc in the boiling sodium hydroxide is written below:
zn (s) + 2 naoii (aq) + 2 h20 (1) ► nazzn(oii)4 (aq) + ii2 (g)
does this equation represent a physical change or a chemical change? how do you know?
physical change

Which statement is a reason to support population regulation? a) it is unethical for us to control birth control rates b) humans have the freedom to produce as many children as desired c) the gap between the rich and poor has been narrowing since 1960 d) billions more people on the earth will intensify many environmental and social problems

Which statement describes evidence of a chemical reaction? a) ice melting eliminate b) water boiling c) lighting a match d) grape juice freezing

The bohr model of the atom explained why emission spectra are discrete. it could also be used to explain the photoelectric effect. which is a correct explanation of the photoelectric effect according to the model?