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Questions in chemistry

📝 Answered - Phosphine (PH3) decomposes at elevated temperatures, yielding gaseous P2 and H2: 2 PH3(g) ⇌ P2(g) + 3 H2(g) Kp = 398 at 873 K If the initial partial pressures are PPH3 = 0.0271 atm, PP2 = 0.863 atm, PH2 = 0.514 atm, calculate Qp. Qp =

📝 Answered - The glass transition (Tg) value of the following polymers: -[-S-]- CH3 -[-O-C-C-O-CO-]- CH3 -[N-CO-CO-N-O-]- PI, polyimide, PPS, polyphenylenesulfide, PC, polycarbonate, Which of the following is correct? a. PI > PC > PPS b. PPS > PC > PI c. PPS = PC > PI d. PI = PPS > PC

📝 Answered - Describe how you can separate a mixture of coffee grains and water?

📝 Answered - 1. Discuss NFTF. 2. A sample of ammonia (NH3) has a molality of 1.6 molal and density of 0.9 g/mL. Calculate the %w/w of NH3. (C3) 3. Wine has a typical alcohol content of 12% (%v/v). If the alcohol volume is 24 mL, what is the volume of wine? (C3)

📝 Answered - What has the same mass as 0.25 mol of copper atoms? A. 0.5 mol of oxygen molecules B. 1 mol of sulphur dioxide molecules C. 1.5 mol of water molecules D. 2 mol of oxygen atoms

📝 Answered - Which reaction shows that the enthalpy of formation of $CS _2$ is $\Delta H_f=89.4$ $kJ / mol$? A. $C (s)+2 S(s) \rightarrow CS _2(1)$ B. $C (s)+2 S(s)+894 kJ \rightarrow CS _2(t)+89.4 kJ$ c. $C (s)+2 S(s)+89.4 kJ \rightarrow CS _2(t)$ D. $C (s)+2 S(s) \rightarrow CS _2(\jmath)+89.4 kJ$

📝 Answered - Adithya wants to classify the following changes as physical or chemical. Can you help him? 1. Melting of ice (P) 2. Ripening of fruits 3. Rusting of iron (P) 4. Spoilage of food 5. Burning of wood (ch) 6. Bursting crackers 7. Burning of camphor (ch) | Physical Changes | Chemical Changes | |---|---| | | |

📝 Answered - Which of the following structures are perspective formulas of the stereoisomers of 2,3-dibromobutane? a. C b. D c. E d. B e. A

📝 Answered - Which cannot be chemically broken down into simpler substances? A. compound B. element C. solution D. mixture

📝 Answered - How much would the freezing point of water decrease if 4 mol of sugar were added to 1 kg of water ( [tex]K_{ f }=1.86^{\circ} C /( mol / kg )[/tex] for water and [tex]i=1[/tex] for sugar)? A. [tex]7.44^{\circ} C[/tex] B. [tex]2.15^{\circ} C[/tex] C. [tex]1.86^{\circ} C[/tex] D. [tex]4.00^{\circ} C[/tex]