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Questions in chemistry

[Terjawab] What is the correct formula for lithium sulfide? LiS2 Li₂S Li₂S LiS

[Terjawab] Consider the chemical equations shown here. [tex] \begin{array}{l} NO(g)+O_3(g) \rightarrow NO_2(g)+O_2(g) \Delta H_1=-198.9 kJ \\ \frac{3}{2} O_2(g) \rightarrow O_3(g) \Delta H_2=142.3 kJ \\ O(g) \rightarrow \frac{1}{2} O_2(g) \Delta H_3=-247.5 kJ \end{array} [/tex] What is [tex]$\Delta H_{\text {rxn }}$[/tex] for the reaction shown below? [tex]$NO(g)+O(g) \rightarrow NO_2(g)$[/tex]

[Terjawab] What law says the total amount of substance at the beginning of a reaction must be equal to the amount of substance at the end of the reaction? A. Law of Conservation of Heat B. Law of Conservation of Moles C. Law of Conservation of Mass D. Law of Conservation of Energy

[Terjawab] $2 C_6 H_6(l)+15 O_2(g)-12 CO_2(g)+6 H_2 O(l) \quad \Delta H^{\circ}=?$ -5195.6 kJ -6338.8 kJ -1260.6 kJ -6534.8 kJ +1260.6 kJ

[Terjawab] What is the formula for the ionic compound formed by calcium and nitrogen? A. CaN B. [tex]Ca _2 N_3[/tex] C. [tex]Ca _3 N_2[/tex] D. CN

[Terjawab] $Zn(s) + HCl(aq) \rightarrow ZnCl_2(aq) + H_2(g)$ A piece of zinc is dropped into $0.1 cm^3$ of $0.1 mol \cdot dm ^{-3} HCl$ and the following data were obtained at 4 second intervals. | Time (s) | Mass of zinc (g) | | -------- | ---------------- | | 0 | 0.016 | | 4 | 0.012 | | 8 | 0.010 | | 12 | 0.009 | | 16 | 0.008 | | 20 | 0.008 | 5.1 Calculate the average rate of the reaction for the first 12 s in $mol ^{-1}$. 5.2 Explain why the mass of the zinc remained constant after 16 s. 5.3 Explain how the rate of the reaction changes as time passes. Answer only INCREASES, DECREASES, or REMAINS THE SAME. 5.4 A graph that shows the amount of $H _2$ gas that was produced against time for this reaction is shown below:

[Terjawab] Fill in the missing information: | symbol | atom or ion? (check all that apply) | number of protons | number of electrons | |---|---|---|---| |$\square$ |$\square$ neutral atom $\square$ cation $\square$ anion | 49 | 47 | | Kr |$\square$ neutral atom $\square$ cation $\square$ anion | $\square$ | $\square$ | | $P ^{2-}$ |$\square$ neutral atom $\square$ cation $\square$ anion | $\square$ | $\square$ |

[Terjawab] 1. Explain the relationship between photon wavelength and photon energy. Is it proportional or inversely proportional? How do you know? 2. Explain the flame test phenomenon. Why can flame tests be performed? What happens to the electrons in the metal atoms of each compound?

[Terjawab] Add or subtract the following measurements. Be sure each answer you enter contains the correct number [tex] \begin{aligned} 14.500 g-0.70 g & =\square g \\ 11.570 g-0.8 g & =\square g \\ 15.5 g+1.320 g & =\square g \end{aligned} [/tex]

[Terjawab] Fill in the missing information: | symbol | | atom or ion? check all that apply | | number of protons | number of electrons | | :----- | :-: | :-------------------------------- | :-: | :---------------- | :---------------- | | 2+ Mg | | cation | | | | | C | | neutral atom | | | | | | | neutral atom | | 51 | 54 |