There are two different isotopes; X and Y, both contain the same number of radioactive substances. If sample X has a longer half-life than Y, compare their rate of radioactive decay.
O A. Rate does not depend on half-life
B. Both of their rates are equal
O C. X has a smaller rate than Y
O D. X has a greater rate than Y

Half life refers to the time for 1/2 of the radioactive atoms to decay.

Suppose that X has a half life of 10 days and Y has a half life of 20 days

If both start out with 1000 radioactive atoms then after 20 days

X would have 250 radioactive atoms and Y would have 500 atoms

The rate of decay is greater for the shorter half life:

In the example given X  must have the smaller rate of decay because it has a longer half life.

the working equation for the angular size is the product of the physical size and 360 degrees divided by the product of two pi and distance from earth. the minimum size would be 0.559 degrees while the maximum size would be 0.49 degrees.