Question 12 (1 point) \( \begin{array}{l}\text { 4) Listen } \\ \text { Medium carbon steel has a carbon content of } 0.35 \% \text {. What is the fractional portion } \\ \text { of carbon in this steel? }\end{array} \).

3. Para las reacciones redox completas que se muestran a continuación: a) divida cada reacción en sus semirreacciones; b) identifique el agente oxidante; c) identifique el agente reductor. a) \( 2 \mathrm{Sr}+\mathrm{O}_{2} \rightarrow 2 \mathrm{SrO} \) b) \( 2 \mathrm{Li}+\mathrm{H}_{2} \rightarrow 2 \mathrm{LiH} \) c) \( 2 \mathrm{Cs}+\mathrm{Br}_{2} \rightarrow 2 \mathrm{CsBr} \) d) \( 3 \mathrm{Mg}+\mathrm{N}_{2} \rightarrow \mathrm{Mg}_{3} \mathrm{~N}_{2} \) e) \( 4 \mathrm{Fe}+3 \mathrm{O}_{2} \rightarrow 2 \mathrm{Fe}_{2} \mathrm{O}_{3} \) f) \( \mathrm{Cl}+2 \mathrm{NaBr}_{2} \rightarrow 2 \mathrm{NaCl}+\mathrm{Br}_{2} \) g) \( \mathrm{Si}+2 \mathrm{~F}_{2} \rightarrow \mathrm{SiF}_{4} \) h) \( \mathrm{H}_{2}+\mathrm{Cl}_{2} \rightarrow 2 \mathrm{HCl} \)

Calculate the density of a cup of tap water at room temperature with a mass of 50.8 g and a volume of 52.1 mL . Round your answer to the appropriate number of sig figs. \( 0.975 \mathrm{~g} / \mathrm{mL} \) \( 1.0 \mathrm{~mL} / \mathrm{g} \)

d) \( \mathrm{C}_{4} \mathrm{H}_{10} \mathrm{O}+\mathrm{O}_{2} \rightarrow \quad \mathrm{CO}_{2}+\mathrm{H}_{2} \mathrm{O} \)

Question 12 (1 point) \( \begin{array}{l}\text { 4) Listen } \\ \text { Medium carbon steel has a carbon content of } 0.35 \% \text {. What is the fractional portion } \\ \text { of carbon in this steel? }\end{array} \).

b) qual é o número de valência dos elementos?