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Questions in chemistry

[Terjawab] Two reactants combine to form one new product. Which of the following best describes this type of chemical reaction? A. Combustion B. Synthesis C. Decomposition D. Single Replacement

[Terjawab] Andy has two samples of liquids. Sample A has a pH of 4, and sample B has a pH of 6. What can Andy conclude about these two samples?

[Terjawab] The symbol for a radioactive nuclide is ${ }_{84}^{210} Po$. Which statement is correct? A. The atomic number of the radioactive nuclide is 210. B. The mass number of the radioactive nuclide is 294. C. The number of neutrons present in the nucleus of each atom is 126. D. The number of protons present in the nucleus of each atom is 210.

[Terjawab] Which best describes a compound such as sodium chloride? A. a pure substance that can be separated into different elements by physical means B. a mixture of two common substances that can be separated by chemical means C. a mixture of two common elements that can be separated by physical means D. a pure substance that can be separated into different elements by chemical means

[Terjawab] 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]

[Terjawab] 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]

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

[Terjawab] 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

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

[Terjawab] 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]