7. If there are 30 grams of iron, 40 grams of water, and hydrogen gas are produced? Fe+H_(2)Oarrow Fe_(2)O_(3)+H_(2) a. 20 c. 40 b. 30 d. 50 8. A balanced chemical equation has equal numbers of atoms of each type on both sides of the e This illustrates the example of. __ a. conservation of energy c. action and reaction b. conservation of mass d. natural selection

7. To determine the amount of hydrogen gas produced, we need to use the balanced chemical equation provided:<br /><br />$Fe + H_{2}O \rightarrow Fe_{2}O_{3} + H_{2}$<br /><br />From the equation, we can see that 1 mole of iron (Fe) reacts with 1 mole of water (H_{2}O) to produce 1 mole of hydrogen gas (H_{2}). <br /><br />Given that there are 30 grams of iron, we can calculate the number of moles of iron using its molar mass, which is approximately 55.85 g/mol.<br /><br />Number of moles of iron = 30 grams / 55.85 g/mol ≈ 0.536 moles<br /><br />Since the reaction is 1:1, the number of moles of hydrogen gas produced will also be 0.536 moles.<br /><br />To find the mass of hydrogen gas produced, we can use the molar mass of hydrogen gas, which is approximately 2.016 g/mol.<br /><br />Mass of hydrogen gas = 0.536 moles * 2.016 g/mol ≈ 1.08 grams<br /><br />Therefore, the amount of hydrogen gas produced is approximately 1.08 grams.<br /><br />8. A balanced chemical equation has equal numbers of atoms of each type on both sides of the equation. This illustrates the example of conservation of mass.<br /><br />In a chemical reaction, the total mass of the reactants is equal to the total mass of the products. This is known as the law of conservation of mass. The law states that matter cannot be created or destroyed, only transformed from one form to another.<br /><br />In a balanced chemical equation, the number of atoms of each element is the same on both sides of the equation. This ensures that the total mass of the reactants is equal to the total mass of the products, in accordance with the law of conservation of mass.<br /><br />Therefore, the correct answer is b. conservation of mass.