If an isotope of some element has a half-life of 300 years, about how much of the isotope atoms will be in a sample after 300 years?

The isotope atom in the sample after 300 years will be half.

Explanation:

If the half life of the isotope of an element is 300 years, after 300 years, in this case the mass of the sample provided will become half of the previous initial mass of the substance. As we know the half life is the time that is required for the element to change or decay. The radioactive isotopes have their own half life which are found to be independent of various factors i.e. temperature, concentration and other chemical changes.  

relative humidity, temperature and dew point -- are bound together in the mathematical relationship below. relative humidity changes when temperatures change. because warm air can hold more water vapor than cool air, relative humidity falls when the temperature rises if no moisture is added to the air. so i would say a

answer: the correct option is d. enzyme

lactase and carbonic anhydrase are the examples of enzymes.

lactase is an enzyme, which is present in the small intestine of mammals. it in the digestion of the disaccharide, lactose ( milk sugar) by converting it into two monosachharide, which are glucose and galactose.

carbonic anhydrase is present in the red blood cells. this enzyme plays significant role in the transport of co₂. it in the conversion of co₂ and h₂o into carbonic acid, which is then dissociated into bicarbonate ions and hydrogen ions.