Answer:
answer is D the answer is D the answer is D
The answer to your question is dna helicase
The decay of Francium produces radium-223 (Ra-223) through a beta decay or into astatine-219 through an alpha decay. The atomic number of Francium is 87, and that of Astatine is 85.
<h3>What is beta decay?</h3>
Beta decay is a type of radioactive decay in which a beta ray is emitted from the nucleus of an atom. During the beta decay, a proton in the nucleus is transformed into a neutron and vice versa which results into change in the number of proton in the nucleus. If a proton is converted to a neutron, then it is said to be β+ decay. And, if a neutron is converted to a proton, then it is said to be β– decay.
In this reaction, an atom of Francium (Fr-223) is undergoing a beta decay to produce radium (Ra-88) by the conversion of a neutron into a proton.
Learn more about decay here:
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Answer:
B. Case-Control
Explanation:
A case-control is a study that compares a group with an outcome of interest (cases) with a group who do not have the outcome (controls). This study aims to looks back retrospectively to compare how frequently the exposure to a risk factor is present in each group and with that to determine the relationship between that risk factor and the outcome.
So in this case, the cases are children with pervasive development disorder and the control is those without the disorders.
These studies are normally observational because no intervention is attempted.
