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Questions in chemistry

[Terjawab] Lars observes a substance to be a solid and to float in water at room temperature ([tex]$23^{\circ} C$[/tex]). Based on the given properties, which substance is the most likely identity of this sample? | Substance | Melting Point ([tex]$^{\circ} C$[/tex]) | Boiling Point ([tex]$^{\circ} C$[/tex]) | Density at Room Temperature ([tex]$g / cm^3$[/tex]) | |---|---|---|---| | carbon tetrachloride | -22.9 | 76.7 | 1.59 | | cetyl alcohol | 49.3 | 344 | 0.811 | | dichlorobenzene | 53.5 | 174 | 1.25 | | Sulfur hexafluoride | -64 | -50.8 | 0.00617 | A. carbon tetrachloride B. cetyl alcohol C. dichlorobenzene D. sulfur hexafluoride

[Terjawab] Jessica has 12.7 moles of a compound for an experiment. How many particles of the compound does she have? A. $2.11 \times 10^{23}$ B. $4.74 \times 10^{23}$ C. $7.65 \times 10^{23}$ D. $4.74 \times 10^{24}$ E. $7.65 \times 10^{24}$

[Terjawab] For the solution description, select a correct characterization from the response list: [tex]pH=2.30[/tex] A. an acidic solution B. a basic solution C. a neutral solution D. a buffer solution

[Terjawab] 3-ethyl-3,4-dimethylnonane

[Terjawab] 0.083 mole of carbohydrate with empirical formula CH₂O contains 1 g of hydrogen. What is the molecular formula of the carbohydrate? Options: (1) C₅H₁₀O₅ (2) C₆H₁₂O₆ (3) C₁₂H₂₂O₁₁ (4) C₆H₁₂O₄

[Terjawab] Which best describes a neutralization reaction? A. a reaction between an acid and a base B. a reaction between two acids C. a reaction between a base and a salt D. a reaction between two salts

[Terjawab] Select the correct answer. Thomas has [tex]$235$[/tex] grams of [tex]$K_2S$[/tex] in the chemistry lab. How many atoms of potassium (K) are in [tex]$235$[/tex] grams of the compound? A. [tex]$2.13 \times 10^{23}$[/tex] B. [tex]$4.26 \times 10^{23}$[/tex] C. [tex]$2.57 \times 10^{24}$[/tex] D. [tex]$3.37 \times 10^{24}$[/tex] E. [tex]$7.08 \times 10^{24}$[/tex]

[Terjawab] In a school's laboratory, students require 50.0 mL of [tex]$2.50 M H _2 SO _4$[/tex] for an experiment, but the only available stock solution of the acid has a concentration of 18.0 M. What volume of the stock solution would they use to make the required solution? Use [tex]$M_i V_i=M_i V_r$[/tex]. A. 0.900 mL B. 1.11 mL C. 6.94 mL D. 7.20 mL

[Terjawab] Which statement accurately describes the chemical symbol of an element? A. The chemical symbol is always a single letter. B. The chemical symbol always starts with the same letter as the name of the element. C. The chemical symbol always begins with a capital letter. D. The chemical symbol can be shared by more than one element.

[Terjawab] Balance these redox reactions by the oxidation number method. [tex]MnO₄⁻ + I⁻⁷ \rightarrow MnO₂ + I₂[/tex]