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Questions in chemistry

[Terjawab] If you need to reverse the following reaction in order for it to be an intermediate reaction in a Hess's law problem, what would be the final value for the enthalpy of reaction you use for this intermediate reaction? [tex]C_2 H_4+3 O_2 \rightarrow 2 CO_2+2 H_2 O, \Delta H=-1410 kJ[/tex] A. 2820 kJ B. -2820 kJ C. 1410 kJ D. -1410 kJ

[Terjawab] What is the temperature of 0.80 mol of a gas stored in a 275 mL cylinder at 175 kPa? Use [tex]$P V=n R T$[/tex] and [tex]$R=8.314 \frac{L \bullet kPa }{ mol \bullet K }$[/tex]. A. 4.6 K B. 7.2 K C. 61 K D. 96 K

[Terjawab] What did the early atomic theory accomplish? A. It started scientific thought about the structure of the atom. B. It established the idea that matter cannot be created or destroyed. C. It provided an accurate description of the atom. D. It proved that the atom was the smallest form of matter.

[Terjawab] Which statement best explains how the solution should be made? A. Add 1.5 mL of [tex]$0.50 M H _2 SO _4$[/tex] to 10.5 mL of water to get 12 mL of [tex]$4 M H _2 SO _4$[/tex]. B. Add 1.5 mL of [tex]$4.00 M H _2 SO _4$[/tex] to 10.5 mL of water to get [tex]$12- mL$[/tex] of [tex]$0.50 M H _2 SO _4$[/tex]. C. Add 1.5 mL of [tex]$4.00 M H _2 SO _4$[/tex] to 12 mL of water to get [tex]$0.50 M H _2 SO _4$[/tex].

[Terjawab] Which of the following factors determines the size of an atom? A. the volume of the nucleus B. the volume of space occupied by the electrons of the atom C. the volume of a single electron, multiplied by the number of electrons in the atom D. the total nuclear charge E. the total mass of the electrons surrounding the nucleus

[Terjawab] What is the empirical formula of $C _8 H _{16} O _8$?

[Terjawab] Which factor can decrease the rate of a chemical reaction? A. low activation energy B. high pressure C. low temperature D. high concentration of enzyme

[Terjawab] Which of the following reactions are disproportionation reactions? (A) Cu⁺ → Cu²⁺ + Cu (B) 2 KMnO₄ → K₂MnO₄ + MnO₂ + 2 H₂O (C) 2 KMnO₄ → K₂MnO₄ + MnO₂ + O₂ (D) 2 MnO₄⁻ + 3 Mn²⁺ + 2 H₂O → 5 MnO₂ + 4 H⁺ Choose the correct answer from the options given below: (A), (B)

[Terjawab] 1. What causes Brownian motion? 2. What was Brown's initial observation? How did Einstein help explain this observation? 3. Explain how an increase in temperature affects Brownian motion. 4. Describe the relationship between temperature and the rate of chemical reactions in a living organism.

[Terjawab] 1. In the industrial preparation of oxygen, state: (a) How dust particles are removed from air. (b) Why carbon (IV) oxide is removed before the mixture is cooled. 2. A form four student accidentally mixed Sodium Carbonate and Calcium. How would he obtain a dry sample of Sodium Carbonate from the mixture?