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Questions in chemistry

[Terjawab] How is the [tex]$\Delta H_{\text {fusion }}$[/tex] used to calculate the energy released when a volume of liquid freezes? A. Liters liquid [tex]$\times 1000 ml / 1 L \times g / ml \times mol / g \times 1 / \Delta H_{\text {fusion }}$[/tex] B. Liters liquid [tex]$\times 1000 ml / 1 L \times ml / g \times g / mol \times \Delta H_{\text {fusion }}$[/tex] C. Liters liquid [tex]$\times 1000 ml / 1 L \times g / ml \times mol / g \times \Delta H_{\text {fusion }}$[/tex] D. Liters liquid [tex]$\times 1000 ml / 1 L \times ml / g \times g / mol \times 1 / \Delta H_{\text {fusion }}$[/tex]

[Terjawab] How many moles are in 23.4 g of [tex]$CaCl_2$[/tex]?

[Terjawab] Express your answer to two significant figures. You form water vapor by mixing oxygen and hydrogen at $730^{\circ} C$ in a 5.4-liter container. This is the equation for the reaction: [tex]$O_2(g)+2 H_2(g) \rightarrow 2 H_2 O(g)$[/tex] The partial pressure of oxygen before the reaction is 122.3 kilopascals, and there is excess hydrogen. How many moles of water are formed? The reaction produces $\square$ moles of water.

[Terjawab] 7. The table shows information about some oxides. | Oxide | Structure | Effect of water | |-------|-------------------|------------------------------| | | Simple molecular | Dissolves to form an acid | For which of the elements nitrogen, phosphorus, sulfur and silicon could this information about their oxides be correct? A) Phosphorus and sulfur only B) Nitrogen and silicon only C) Nitrogen, phosphorus and sulfur only D) Nitrogen, phosphorus, sulfur and silicon 8. The table contains information about four substances. Which substance is an ionic compound? | | State at room temperature | Conducts electricity at room temperature | Conducts electricity when molten | Conducts electricity when in aqueous solution | |-----|---------------------------|-----------------------------------------|---------------------------------|----------------------------------------------| | A | Liquid | X | X | | | B | Solid | ✓ | ✓ | Insoluble | | C | Solid | ✓ | ✓ | | | D | Solid | X | | ✓ | 9. An ionic compound has the formula Al₂O₃. What are the charges on the ions? A) Al⁺ O⁻ B) Al²⁺ O²⁻ C) Al²⁺ O³⁻ D) Al³⁺ O²⁻ 10. Which equation is correct for the reaction between carbon dioxide and magnesium hydroxide? A) CO₂ + Mg(OH)₂ → MgCO₃ + H₂O B) CO₂ + 2Mg(OH)₂ → 2MgCO₃ + 2H₂O C) 2CO₂ + Mg(OH)₂ → MgCO₃ + H₂O D) 2CO₂ + Mg(OH)₂ → 2MgCO₃ + H₂O

[Terjawab] $HBr+KOH \rightarrow KBr+H_2 O$ In this reaction, the acid is A. HBr B. KOH C. KBr D. $H _2 O$

[Terjawab] What volume, in liters, of $1.0 M C_6 H_{12} O_6$ solution can be made using $360.4 g C_6 H_{12} O_6$? $C_6 H_{12} O_6: 180.2 g / mol$

[Terjawab] Which condition must be met in order for an equation to be balanced? A. The elements in the reactants are the same as the elements in the products. B. There are fewer elements in the reactants than there are in the products. C. The number of atoms in the reactants is greater than the number of atoms in the products. D. The number of atoms in the reactants equals the number of atoms in the products.

[Terjawab] Which substances are most likely acids? Check all that apply. [tex]$CH _4$[/tex] HI [tex]$NH _3$[/tex] [tex]$HNO _3$[/tex] NaCl

[Terjawab] The half-life of a particular radioactive substance is 1 year. If you started with 220 grams of this substance, how much of it would remain after 7 years? Remaining Amount $=I(1-r)^t$ grams

[Terjawab] Consider the following chemical reaction in equilibrium: [tex]$CH_3 COOH \Leftrightarrow CH_3 COO^{-}(a q)+H^{+}(a q)$[/tex] What will happen to the chemical equilibrium if [tex]$MgCl _2$[/tex] is added? A. The chemical equilibrium of the system will be unaffected. B. The chemical equilibrium of the system will shift to the right to favor the forward reaction. C. The chemical equilibrium of the system will be damaged irreversibly.