What is the standard enthalpy change of a chemical reaction denoted as?

• A.H

• ΔΗ

• A.H

According to convention, what is the oxidation number of F in a compound?

• 0

• +1

• 42

When KNO3 is heated to 550 °C, what type of reaction occurs?

• Decomposition

• Exothermic, ΔH < 0

• Endothermic, ΔH < 0

What is the main chemical composition of apatite, a common ore in nature that contains fluorine?

• CaF₂

• NaF

• Na3AlF6

• Ca3(PO4)2F

Arrange the following compounds in order of increasing oxidation state of Mn from right to left.

• MnCl2; Mn2(SO4)3; MnO₂; K2MnO4; KMnO4

• Mn; MnO₂; K2MnO4; KMnO4

• MnCl2; Mn(SO4); Mn; MnO₂; K2MnO4

Which statement about the sign of reaction enthalpy (ΔH) is correct?

• Endothermic reactions have ΔH < 0

• Exothermic reactions have ΔH > 0

• Endothermic reactions have ΔH = 0

Which statement is false?

• The atomic radius of chlorine is larger than that of fluorine.

• Fluorine has a stronger oxidizing power than chlorine.

• The electronegativity of bromine is greater than that of iodine.

• In compounds, fluorine and chlorine have oxidation states of -1, +1, +3, +5, +7.

Which indicator is commonly used to identify solution b?

• Phenolphthalein

• Starch

• Litmus

• Lime water

What is the oxidizing agent?

• Gives electrons, contains an element with an increasing oxidation state after the reaction.

• Gives electrons, contains an element with a decreasing oxidation state after the reaction.

• Receives electrons, contains an element with an increasing oxidation state after the reaction.

• Receives electrons, contains an element with a decreasing oxidation state after the reaction.

The standard enthalpy of formation for a substance dissolved in solution is determined under what concentration condition?

• 0.01 mol/L

• 1 mol/L

• 0.1 mol/L

• 0.5 mol/L