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Questions in chemistry

📝 Answered - What is a chemical change? Provide two examples.

📝 Answered - Match the following List-I with List-II and choose the correct option. List-I (P) ⁴⁰₁₈Ar and ⁴⁰₁₉K (Q) ¹²₆C, ¹³₆C and ¹⁴₆C (R) ¹⁶₈O, ¹⁵₇N and ¹⁴₆C (S) ¹⁹₉F, ³⁹₁₉K and ²³₁₁Na List-II (1) Isodiaphers (2) Isotones (3) Isotopes (4) Isobars

📝 Answered - Consider this reaction: [tex]$H_2S + Ba(OH)_2 \rightarrow 2H_2O + BaS$[/tex] Which compound is acting as a base in this reaction? A. [tex]$H_2S$[/tex] B. [tex]$Ba(OH)_2$[/tex] C. [tex]$H_2O$[/tex] D. BaS

📝 Answered - A bicycle tire has a volume of 1.0 L at $22^{\circ} C$. If the temperature of the tire is increased to $52^{\circ} C$, what is the resulting volume of the tire? Type in your answer using the correct number of significant figures. Use the formula for Charles' Law: $\frac{V_1}{T_1}=\frac{V_2}{T_2}$

📝 Answered - The equation $H _3 PO _4+3 KOH \rightarrow K _3 PO _4 + 3 H _2 O$ is an example of which type of reaction? synthesis reaction single replacement reaction double replacement reaction decomposition reaction

📝 Answered - Calculate the mass of ammonium sulfide $(NH_4)_2S$ in 3.00 L of a 0.0200 M solution.

📝 Answered - 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]

📝 Answered - How many moles are in 23.4 g of [tex]$CaCl_2$[/tex]?

📝 Answered - 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.

📝 Answered - 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