Question

directions: below are the essay questions on your test. please prepare your answers now and use this sheet to help you write your answers on the test. do not copy any answers from brainly or any other outside sources. your answer must come from information provided in the lessons. do not post these questions on any answer site. that is a direct violation of the honor code. 1) use the equation to complete the activity. ( _{86}^{219}\text{rn}
ightarrow_{84}^{215}\text{po}+alpha ) the nuclear equation shows the transmutation of a form of radon into polonium and an alpha - particle. in one to two sentences, explain whether or not the reaction is balanced. 2) scientists used to believe that chemical reactions fueled the sun. why did this lead them to believe that the sun was very young? what kind of reactions do we now think are responsible for the energy released by the sun? in one to two sentences, explain your reasoning.

Explanation:

Step1: Recall radioactive - decay types

Alpha - decay involves the emission of an alpha particle, which is a helium - 4 nucleus ($_{2}^{4}\alpha$).

Step2: Analyze the given reaction

The reaction $_{86}^{219}Rn
ightarrow_{84}^{215}Po + \alpha$ is an alpha - decay. In alpha - decay, the atomic number of the parent nucleus decreases by 2 and the mass number decreases by 4. Here, for radon ($Rn$) with atomic number 86 and mass number 219, after emitting an alpha particle, it forms polonium ($Po$) with atomic number 84 (86 - 2) and mass number 215 (219 - 4).

Step3: Answer question 1

The activity is alpha - decay. The atomic number and mass number are conserved in the reaction. The sum of atomic numbers on the right - hand side (84+2) is equal to the atomic number of the parent nucleus (86), and the sum of mass numbers on the right - hand side (215 + 4) is equal to the mass number of the parent nucleus (219), so the reaction is balanced.

Step4: Answer question 2

The sun is now believed to be powered by nuclear fusion reactions, not chemical reactions. Chemical reactions involve the rearrangement of electrons, while nuclear reactions involve changes in the nucleus. The energy released by the sun is much too large to be explained by chemical reactions. Nuclear fusion reactions, such as the fusion of hydrogen into helium, release a vast amount of energy through the conversion of mass into energy according to Einstein's equation $E = mc^{2}$.

Answer:

1. The reaction $_{86}^{219}Rn

ightarrow_{84}^{215}Po+\alpha$ is an alpha - decay and is balanced because the atomic number and mass number are conserved.

1. Scientists now think the sun is powered by nuclear fusion reactions, not chemical reactions. Chemical reactions cannot account for the vast amount of energy released by the sun, while nuclear fusion can, as it converts mass into energy according to $E = mc^{2}$.