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Questions in chemistry

[Done] How did researchers detect whether da Vinci's paint contained walnut oil? A. The paint was dissolved in water, and the oil rose to the top. B. The paint was exposed to infrared absorption analysis. C. The paint was used in PCR (polymerase chain reaction) to detect walnut DNA. D. Somebody actually tasted it, and it tasted like oily walnuts.

[Done] Sodium chloride reacts with copper sulfate to produce sodium sulfate and copper chloride [tex]2 NaCl(aq)+CuSO_4(aq) \rightarrow Na_2 SO_4(aq)+CuCl_2(s)[/tex] This equation represents a A. synthesis reaction. B. decomposition reaction. C. single replacement reaction. D. double replacement reaction.

[Done] What is the pH of [tex]$6.30 \times 10^{-5} M HCl (H^+)$[/tex] solution?

[Done] Consider the chemical equilibrium of the reaction: [tex]$NH_4 OH(aq) \Leftrightarrow NH_4^{+}(aq)+OH^{-}(aq)$[/tex] What will happen to the chemical equilibrium if [tex]$NH _4 Cl$[/tex] is added to this solution? A. The chemical equilibrium will shift to the right. B. The chemical equilibrium will not shift. C. The chemical equilibrium will shift to the left.

[Done] A substance that increases the concentration of hydrogen ions when placed in water because it donates, or releases, H+ ions is a(n):

[Done] 1. Which of the following is not considered as matter? a. Air b. Water c. Sun d. Light 2. The intermolecular force of attraction is maximum in a. Solids b. Liquids c. Gases d. Both a and c 3. Fluidity is maximum in a. Solids b. Liquids c. Gases d. All of these 4. Gases a. Cannot be compressed easily b. Occupy the entire space in the container c. Have a definite shape d. Cannot flow 5. Which of the following have only one free surface? a. Solids b. Liquids c. Gases d. All of these

[Done] 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

[Done] 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. $7.65 \times 10^{24}$

[Done] 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

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