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Questions in chemistry

[Answered] The initial temperature of a bomb calorimeter is [tex]$28.50^{\circ} C$[/tex]. When a chemist carries out a reaction in this calorimeter, its temperature decreases to [tex]$27.45^{\circ} C$[/tex]. If the calorimeter has a mass of 1.400 kg and a specific heat of [tex]$3.52 J /\left( g \cdot{ }^{\circ} C \right)$[/tex], how much heat is absorbed by the reaction? Use [tex]$q=m C_p \Delta T$[/tex]. A. 140 J B. 418 J C. [tex]$1,470 J$[/tex] D. [tex]$5,170 J$[/tex]

[Answered] Caffeine, the active ingredient in coffee, is composed of eight atoms of carbon, ten atoms of hydrogen, four atoms of nitrogen, and two atoms of oxygen. The chemical formula of caffeine is: [tex]$C _8 H _{10} N_4 O$[/tex] [tex]$C _8 H _{12} N_4 O _4$[/tex] CHNO [tex]$C _8 H _{10} N_4$[/tex] [tex]$C _8 H _{10} N_4 O _2$[/tex]

[Answered] Find the weight (in mg) of one atom of gold, AU (196.97)

[Answered] The equation for the reaction between aluminium and copper (II) oxide is: [tex]2 Al+3 CuO \longrightarrow Al_2 O_3+3 Cu[/tex] Which statements about this equation are correct? 1. The oxidation number of the aluminium reactant is +2 2. The oxidation number of the aluminium in the product is +6 3. The oxidation number of the aluminium in the reactant is +2 4. The oxidation number of the copper product is 0. Please mark 1 answer. A. 1, 2, and 3

[Answered] What is the name of this ion? [tex]$H_3 O^{+}$[/tex] A. water positive B. hydrate C. trihydrogen oxide D. hydronium

[Answered] Which solution has the greatest number of hydrogen ions? A. blood, [tex]pH =7.2[/tex] B. lemon juice, [tex]pH =2[/tex] C. soda, [tex]pH =3.5[/tex] D. bleach, [tex]pH =13.5[/tex]

[Answered] Select the correct answer. Which notation is used to represent an alpha particle? A. ${ }_{-1}^0 \beta$ B. ${ }_0^0 y$ C. ${ }_2^4 He$ D. ${ }_1^0 n

[Answered] For elements belonging to Group 5 of the periodic table, determine the number of valence electrons.

[Answered] Consider the following reversible reaction. [tex]C(s)+O_2(g) \leftrightarrow CO_2(g)[/tex] What is the equilibrium constant expression for the given system? A. [tex]K _{e q}=\frac{\left[ CO _2\right]}{[ C ]\left[ O _2\right]}[/tex] B. [tex]K _{\text {eq }}=\frac{\left[ CO _2\right]}{\left[ O _2\right]}[/tex] C. [tex]K _{e q}=\frac{\left[ C ^3\left[ O _2\right]\right.}{\left[ CO _2\right]}[/tex] D. [tex]K _{e q}=\frac{\left[ O _2\right]}{\left[ CO _2\right]}[/tex]

[Answered] Select the best answer for the question. 17. How does an oil acid test kit indicate the presence of acid? A. The color changes B. The liquid in the sample tube boils C. The word "acidic" appears on the test strip D. The test kit produces a strong pungent odor