Answer:
The two elements are POLONIUM and RADIUM.
Explanation:
Maria Curie is a French physicist and chemist, though she was of a Polish naturals. She was the first woman to receive a Noble Price which she earned for conducting leading and head way research on radioactivity. She discovered the theory of radioactivity; also the techniques isolating radioactive isotopes. These helped her and her husband discover Polium and Radium.
Answer: <u>Four</u>Explanation: Calcium Sulfide is an ionic compound made up of Ca²⁺ and S²⁻.
Ca²⁺ is formed as,
Ca → Ca²⁺ + 2 e⁻
These two electrons are accepte by Sulfur as,
S + 2 e⁻ → S²⁻
So, before accepting 2 electrons S was having six valence electrons, after accepting two electrons from Ca it has 8 electrons which are present in four pairs as shown below,
Main sequence stars with low temperatures tend to have low luminosity is based on Hertzprung-Russell diagram
<h3>What is the Hertzsprung-Russell diagram's main sequence?</h3>
The bright, hot stars in the image's upper left are the main sequence group, which stretches roughly diagonally to the lower right (dim and cool). In the bottom left are white dwarfs, which are small, faint, and hot. In the top right are giant and supergiant stars, which are big, bright, and cool.
<h3>What is the main sequence star H-R diagram trend?</h3>
Main sequence stars have a wide range of effective temperatures, but because they are brighter at higher temperatures, they normally follow a band from the bottom right to the top left of the diagram. Inside the cores, hydrogen and helium are fusing together.
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