What characteristic of radiation allows a geiger counter to measure radiation levels?
the ability of radiation to expose photographic film
the ability of radiation to ionize gas particles
the inability of radiation to conduct electricity
the inability of radiation to pass through lead

The correct answer is option B. The ability of radiation to ionize gas particles.

The Geiger counter detects the nuclear radiations such as alpha, beta, gamma radiations ,etc. The geiger tube is filled with inert gases and high voltage is applied to the tube. Such that when the incident radiation ionizes the gas present inside, the radiation can be detected. Thus, the geiger counter works on the the ability of radiation to ionize gas particles.

And a) oxygen i believe

You would do 1500/4 and the answer is 375