Are the whole numbers closed under subtraction?
Your subtractions may be like this:
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Take as many examples as possible and check.

Are the whole numbers closed under division? Now observer this table Confirm it by taking few more examples.

Are the integers are associative under subtraction? Explain with an example.

Subtraction of whole numbers may not be closure. Reason?

Is subtraction associative in rational numbers ? Explain with an example.

Subtraction of whole numbers is not commutative state reason?

(A) In multiplication or division, the final result should retain only that many significant figures as are there in the original number with the least number of significant figures. (B) In addition or subtraction the final result should retain only that many decimal places as are there in the number with the least number of decial places.

Is the associative property true for the whole numbers? Take many more examples and verify.

Radioactive decay is a statisticle process i.e., we cannot precisely predict the timing of a particular radioactivity of a particular nucleus . The nucleus can disintegrate immediately or it may take infinite time . Simply the probability of the number of nuclei being disintegrated at any instant can be predicted . the rate at which a particular decay process in a radioactive sample is directly proportional to the number of radioactive nuclei present and thus obeys first order kinetics . the factor dN/N expresses the fraction of nuclei decayed in time dt. t_(1//2) is the time in which half of the atoms are decayed and average life is the time for the nucleus to survive before decay . A freshly prepared radioactive source of half period 2 hour emits radiations on intensity which is 64 times of the permissible safe level. The minimum time after which it would be possible to work with this source is :