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Questions in chemistry

[Terjawab] Propane $(C_3H_8(g), \Delta H_f = -103.8 \text{ kJ/mol})$ reacts with oxygen to produce carbon dioxide $(CO_2, \Delta H_f = -393.5 \text{ kJ/mol})$ and water $(H_2O, \Delta H_f = -241.82 \text{ kJ/mol})$ according to the equation below: $C_3H_8(g) + 5O_2(g) \rightarrow 3CO_2(g) + 4H_2O(g)$ What is the enthalpy of combustion (per mole) of $C_3H_8(g)$? Use $\Delta H_{\text{rxn}} = \sum(\Delta H_{\text{f, products}}) - \sum(\Delta H_{\text{f, reactants}})$. A. -2,044.0 kJ/mol B. -531.5 kJ/mol C. 531.5 kJ/mol D. 2,044.0 kJ/mol

[Terjawab] Fill in the blanks. 11. Soy sauce and water is (a uniform / not a uniform) mixture because ____. 12. Peas and carrots (a uniform) mixture because ____. 13. Glue and water is (a uniform / non-uniform) mixture because ____. 14. Spaghetti and meatballs is (a homogeneous / heterogeneous mixture) because ____. 15. Salt and water is (a homogeneous / heterogeneous mixture) because ____. Classify the following mixture as homogeneous or heterogeneous. 16. Vegetable 17. Halo-halo 18. Air 19. Table salt and water 20. Concrete materials

[Terjawab] I. Concentration II. Temperature of reactants III. Surface area of reactants Please mark 1 answer: A. I and III only B. I and II only C. I, II and III D. II and III only 3A (aq) -> 2B (aq) + C (aq), the decomposition of compound A at 300 K in a solution with constant volume can be followed by monitoring the concentration of A. Initially, the concentration of A is 2.94 mol dm⁻³, and after 1.3 min, it is reduced to 1.76 mol dm⁻³. Calculate the rate of the reaction. Please mark 1 answer: A. 5 x 10³ mol dm⁻³ s⁻¹ B. 0.0504 mol dm⁻³ s⁻¹ C. 3 x 10² mol dm⁻³ s⁻¹ D. 3.8 x 10³ mol dm⁻³ s⁻¹

[Terjawab] Since kerosene is a "combustible", it should have a flashpoint ___ degrees Fahrenheit. A. of less than 32 B. of less than 100 C. between 100 and 200 D. of more than 200

[Terjawab] Matter can change from one state to another when energy (usually heat) is added or removed: - Melting: Solid to liquid (e.g., ice melting into water) - Freezing: Liquid to solid (e.g., water freezing into ice) - Evaporation: Liquid to gas (e.g., water turning into steam) - Condensation: Gas to liquid (e.g., steam turning back into water droplets) - Sublimation: Solid directly to gas (e.g., dry ice turning into carbon dioxide gas) C. (COPY AND ANSWER) ACTIVITY NOTEBOOK Directions: 1. Look around your house and find 2 examples of each state of matter: solid, liquid, and gas. 2. List them in the correct column in the table below. 3. Write what you observed that helped you decide the state of matter for each item. | State of Matter | Example from Home | What I Observed | | :-------------- | :---------------- | :------------- | | Solid | 1. | | | | 2. | | | Liquid | 1. | | | | 2. | | | Gas | 1. | | | | 2. | |

[Terjawab] What are the two parts of an atom? A. the nucleus and the proton cloud B. the neutron and the electron cloud C. the neutron and the proton cloud D. the nucleus and the electron cloud

[Terjawab] Under which conditions would the solubility of a gas be greatest? A. high pressure and high temperature B. high pressure and low temperature C. low pressure and high temperature D. low pressure and low temperature

[Terjawab] Which element is a noble gas? uranium, U oxygen, 0 cobalt, Co neon, Ne

[Terjawab] The atomic number and mass number of an element are 15 and 31. a. What is the number of valence electrons in this atom? b. How many neutrons are present in this atom? c. Draw the orbit electron configuration of this atom.

[Terjawab] Which is a characteristic of mixtures? A. They are chemically bonded together. B. They can be classified as pure substances. C. They have fixed ratios between their components. D. They can be separated by physical processes.