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Questions in chemistry

[Done] Which of these statements explains the relationship among elements, compounds, and mixtures? A. Elements are made of compounds and mixtures. B. Both compounds and mixtures are made up of elements. C. Mixtures are made of elements, and elements are made of compounds. D. Compounds are made of mixtures, and mixtures are made of elements.

[Done] True or False: A gas that produces a pop with a burning splint is carbon dioxide.

[Done] True or False A gas that ignites a glowing splint is oxygen.

[Done] 2. Newton began his academic career in 1667. For how long was he a working scientist? Was he a very productive scientist? Justify your answer.

[Done] What is the energy needed to raise an electron in the hydrogen atom from the second energy level to the third energy level? A. \(1.52 \times 10^4 \, \text{J}\) B. \(3.63 \times 10^{-19} \, \text{J}\) C. \(2.18 \times 10^{-19} \, \text{J}\) D. \(4.48 \times 10^{-9} \, \text{J}\) E. \(3.03 \times 10^{-19} \, \text{J}\)

[Done] How many molecules are there in 79 g of [tex]\text{Fe}_2\text{O}_3[/tex]? How many atoms are in this amount?

[Done] 48 dm\(^3\) of a gas has a mass of 262 g. a. How many moles is this? b. What is the \(M_r\)? c. What must this element be?

[Done] What do you notice about the elements on the reactant and product sides of the equation?

[Done] An ideal gas in a sealed container has an initial volume of 2.55 L. At constant pressure, it cools to 16.00 degrees Celsius, resulting in a final volume of 1.75 L. What was the initial temperature?

[Done] Explain the reason for sodium's location in the periodic table, detailing both its position in its group and its period.