The half-life of radium is 1690 years. If 20 grams are present now, how much will be present in 100 years?

Example: 50. OmL of monoprotic acid solution of unknown concentration is titrated with 0.32 M of NaOH. It takes 24.6 mL of this base to reach the endpoint. What is the molarity of this acid?

4. \( \mathrm{H}-\mathrm{CH} * \mathrm{O} \) 5. \( \mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CO}-\mathrm{CH}_{3} \) 6. \( \mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{O}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{3} \) 7. \( \mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{NH}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{3} \) 8. \( \mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{OH} \) 9. \( \mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH} * \mathrm{O} \) 10. \( \mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}-\mathrm{F} \) 11. \( \mathrm{CH}_{3}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CO}-\mathrm{CH}_{2}-\mathrm{CH}_{2}-\mathrm{CH}_{3} \)

\( \mathrm{LiOH}+\mathrm{HBr} \rightarrow \mathrm{LiBr}+\mathrm{H}_{2} \mathrm{O} \) If you start with 10.0 grams of lithium hydroxide, how many grams of lithium bromide will be produced?

ALCANOS:ENLACES SIMPLE 1- 2,3 DIMETIL HEXANO 2- 2-ETIL 3.3- DIMETIL-5-ISOPROPIL-OCTANO 3- 3-METIL-2,6,7-TRIETIL-NONANO 4- 2-BUTIL-3,5,7-TRIMETIL- DECANO 5- 3-ETIL-5,7-DIMETIL-4-PROPIL-DODECANO

Balancea por óxido - reducción las ecuaciones siguientes: \( \begin{array}{l}\text { 1) } \mathrm{HNO}_{3}+\mathrm{S} \\ \begin{array}{l}\text { Semireacción de oxidación } \\ \text { Agente oxidante } \longrightarrow\end{array} \\ \mathrm{NO}_{2}+\end{array} \mathrm{H}_{2} \mathrm{SO}_{4}+\mathrm{H}_{2} \mathrm{O} \) \( \begin{array}{l}\text { Semireacción de reducción } \\ \text { Agente reductos }\end{array} \)