Why are the classification systems changing every now and then?

During the summer, the level of water in a pond decreases by 2 inches every week due to evaporation. What is the change in the level of water over a period of 6 weeks?

Assume that the rate at which radioactive nuclei decay is proportioanl to the number of such nuclei that are present in a given sample. In a certain sample 10% of the original number of radioactive nuclei have undergone disintegration in a period of 100 years. What percentage of the original radioactive nuclei will remain after 1000 years.?

Assume that the rate at which radioactive nuclei decay is proportional to the number of such nuclei that are present in a given sample. In a certain sample 10% of the original number of radioactive nuclei have undergone disintegration in a period of 100 years. What percentage of the original radioactive nuclei will remain after 1000 years?

___changes which take place within a short period of time.

Assertion : Water hyacinth is an invasive aquatic plant which speads all over the water in a short period of time. Reason : Water hyacinth can reproduce vegetatively.

Energy resources can be renewed over a short period of time is known as _______ .

Half-life period of a radioactive element is 100 seconds. Calculate the disintegration constant and average life period. How much time will it take for 90% decay?

. . . . . . . .. Is the gradual change occuring in leving organisms over a period of time.

Change in linear momentum can be produced by applying larger force for a longer period of time.