Answer:
Answer is B.
Explanation:
<u>Period is duration of time</u>.
Period can be of a second,minute,hour or of Some years.We will give unit according to the duration of time.In the given options second is most obvious because it is used to measure time.
Answer:
D
Explanation:
Bohr determined that there are discrete (unique, different from one another) energy levels in the atom and that electrons will orbit the nucleus within these energy levels, known as orbitals.
Answer:
there r not only 2 types of nests
Cup nest.
Adherent nests.
Platform nests.
Earth-hole nests.
Ground and mound nests.
Scrape nests.
Explanation:
Answer:a
a possible explanation for this occurrence is that a test tube or dropper was accidentally used repeatedly without being sterilized, causing sample cross-contamination. DNA in this test case did not confirm that the father of the second child was another client of the fertility clinic who had never met the mother...therefore this is a possibility.
Explanation: