1. Is the following sentence true or false? The new substances formed as a result of a chemical reaction are called products. 2. Circle the letter of each sentence that is a correct interpretation of the chemical equation \( \mathrm{C}+\mathrm{O}_{2} \longrightarrow \mathrm{CO}_{2} \). a. Carbon and oxygen react and form carbon monoxide. b. Carbon and oxygen react and form carbon dioxide. c. Carbon dioxide yields carbon and oxygen. d. The reaction of carbon and oxygen yields carbon dioxide. 3. Is the following sentence true or false? The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction.

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 ? \( \begin{array}{ll}\text { (a) } 15 \mathrm{e}^{-} & \text {(b) } 31 \mathrm{e}^{-} \\ \text {(c) } 32 \mathrm{e}^{-} & \text {(d) } 46 \mathrm{e}^{-}\end{array} \)

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 \( 30.0^{\circ} \mathrm{C} \) ?

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

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: \( \mathrm{C}_{(\mathrm{grffte})}+\frac{1}{2} \mathrm{O}_{2(g)} \rightarrow \mathrm{CO}_{(\mathfrak{g})} \quad \Delta H_{1}=-110,3 \mathrm{KJ} \) \( \mathrm{CO}_{(g)}+\frac{1}{2} \mathrm{O}_{2(g)} \rightarrow \mathrm{CO}_{2(g)} \quad \Delta H_{2}=-283,0 \mathrm{KJ} \)

6. Aluminum reacts with oxygen according to the following reaction: \[ 4 \mathrm{Al}(s)+3 \mathrm{O}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{Al}_{2} \mathrm{O}_{3}(s) \] How many liters of oxygen gas at STP are required to completely react with 55.0 g of aluminum?