The simple trick which one can consider in such problem where it is asked for positron emission is :
<span>When the atomic number goes DOWN by one and mass number remains unchanged, then a positron is emitted.
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<span>a. </span>

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Here the atomic number decreases by one.
Similarly, options b and d are eliminated.
Option c is also not the answer.
For c, Count the atomic number on left side and compare it with right side. You will see it is 9 on left and 8 on right. Atomic no. did go down by 1. But the atomic mass is changed as well.
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The colored light emitted is energy and in order to emit energy the element should first obtain energy. The energy absorbed by the substance can be in the form of radiation, heat or electricity. Hope this answers the question. Have a nice day.
Answer:
Alkanes naturally occur in crude oil and are a major component of many fuels and solvents derived from petroleum
Without any ionization, the element (Cn) would have 112 electrons because the atomic number of an element is the number of protons the element has and a neutral element has the same number of electrons as it does protons.
<u>Answer</u>:
Electric evaporator has been used to clean up the Chernobyl and 3 mile island accident.
<u>Explanation</u>:
About 14 years back, there was a puff of radioactive steam from the evaporator used in the "Three-mile island" nuclear plant. It took two years for the electric evaporator to clean up the 2.2 million gallons of water that have been destroyed because of the nuclear power plant accident.
The steam that came out of the electric evaporator carried a radioactive form of hydrogen and tritium with itself. Cost of clean up was $1 billion.