Question

11) 11) Consider the two beakers labeled A and B. Beaker A cor Beaker B contains 1 mole of lead atoms. W known with certainty? A and B. Beaker A contains 1 mole of iron atoms, and ains I mole of lead atoms. Which statement concerning these samples is I mole Beaker A Beaker B A) Beakers A and B contain an equal volume of atoms. B) Beakers A and B contain equal masses of atoms. C) Beakers A and B contain samples with the same density. D) Beakers A and B contain an equal number of atoms. E) None of these are correct. 12) 12) The chemical equation below is unbalanced. What is the coefficient of water when the equation is balanced? Mg(OH)2(5) + HCI(g) MgCl2(5) + H2007 A) 4 B) 2 C) 3 D) 1 E) No coefficient would be shown. 13) 13) Aluminum metal and oxygen gas are produced when aluminum oxide is heated at high temperature. Which statement concerning this chemical change is true? A) The chemical equation for this reaction is: AIO 2(3) Al(s) + O2(g). B) Aluminum and oxygen are the reactants in this reaction. C) Aluminum oxide is the product in this reaction. D) This reaction is a decomposition reaction. E) This reaction is a combustion reaction. 14) The unbalanced equation for the combustion of octane, a component of gasoline, is shown below. What would be the coefficient of carbon dioxide once the equation is balanced? CgH18(7) + O2(g) → CO2(g) + H20(1) A) No coefficient would be shown. B) 16 C) 18 D) 8 E) 25

Answer 1

11)

Since number of mol is same for both, number of atoms will be same for both.

Because number of atom = number of mol * Avogadro’s number

They have different mass because Fe and Pb have different molar mass.

They will have different volume because they have different mass and density.

Answer: D

12)

The reaction is:

Mg(OH)2(s) + HCl(g) -> MgCl2(s) + H2O(l)

Balance Cl:

Mg(OH)2(s) + 2 HCl(g) -> MgCl2(s) + H2O(l)

Balance H:

Mg(OH)2(s) + 2 HCl(g) -> MgCl2(s) + 2 H2O(l)

The equation is now balanced

So, the coefficient of H2O is 2

Answer: B

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