12. 632 g margansovka qizdirilganda \( 33,6 / \) (n.sh da) \( \mathrm{O}_{2} \) hosil bo'lsa, margansovka tarkibidagi sof moddaning massa ulushini hisoblang \( \begin{array}{llll}\text { A) } 0,65 & \text { B) } 0,70 & \text { C) } 0,75 & \text { D) } 0,85\end{array} \)

6. If 380 g of cottonseed oil measures 415 mL , what is its specific gravity? 7. If \( 2 \mathrm{fl} \). oz. of glycerol weighs 74.1 g , what is its specific gravity? 8. Five pints of diluted hydrochloric acid weights 2.79 kg . Calculate its specific gravity.

Consider the same reaction as in question 6 above: \[ 4 \mathrm{Al}(s)+3 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{Al}_{2} \mathrm{O}_{3}(s) \] How many grams of aluminum oxide will be produced from the complete reaction of 1.27 L of oxygen gas at 783.0 mmHg and \( 30.0^{\circ} \mathrm{C} \) ?

Questão 2) Qual o valor da variação de entalpia da reação a seguir? \[ C_{(g r \text { fite })}+\mathrm{O}_{2(g)} \rightarrow \mathrm{CO}_{2(g)} \] Dados: \( \mathrm{C}_{(\mathrm{grffte})}+\frac{1}{2} \mathrm{O}_{2(g)} \rightarrow \mathrm{CO}_{(\mathfrak{g})} \quad \Delta H_{1}=-110,3 \mathrm{KJ} \) \( \mathrm{CO}_{(g)}+\frac{1}{2} \mathrm{O}_{2(g)} \rightarrow \mathrm{CO}_{2(g)} \quad \Delta H_{2}=-283,0 \mathrm{KJ} \)

14 Nitrogen has atomic number 7 and oxygen has atomic number 8 What is total number of electrons in \( \left(\mathrm{NO}_{3}\right)^{-} \)ion ? \( \begin{array}{ll}\text { (a) } 15 \mathrm{e}^{-} & \text {(b) } 31 \mathrm{e}^{-} \\ \text {(c) } 32 \mathrm{e}^{-} & \text {(d) } 46 \mathrm{e}^{-}\end{array} \)

possible Find the hydrogen ion concentration of a solution whose pH is 7.1 . Use the formula \( \mathrm{pH}=-\log \left[\mathrm{H}^{+}\right] \)