How does the Doppler effect explain why a siren's pitch increases as it approaches you A. the siren's moves closer to sound waves it has already produced

B. the sirens moves away from sound waves it has already produced decreasing their wavelength

C. the siren moves away from sound waves it has already produced increasing their wavelength

D. the siren moves closer to sound waves it has already produced increasing their wavelength

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.

nacl or sodium chloride is an ionic compound. this is because an ionic compound pertains to a compound that consists of positively and negatively charged ions. in this case, na (sodium) has a tendency to lose one electron when it reacts with with other atoms, so the resulting sodium ion contains 11 protons and 10 electrons, thus making it positively charged (na+), when chlorine reacts, it usually gains one electron to form an ion called chloride, thus making it negatively charged ( since the ions are oppositely charged, they attract.