Question

26) Diamond is a pure form of the element carbon. If a 2 carat diamond has a mass of \(0.39626\) ) g. how many carbon atoms are contained in this diamond?

A) \(2.38 \times 10^{23}\) atoms

B) \(1.99 \times 10^{23}\) atoms

C) \(1.99 \times 10^{22}\) atoms

D) \(3.97 \times 10^{22}\) atoms

E) \(6.58 \times 10^{-25}\) atoms

27) Dinitrogen monoxide, or laughing gas \(\left(\mathrm{N}_{2} \mathrm{O}\right)\), is used as a dental anesthetic and as an aerosol propellant. How many molecules of \(\mathrm{N}_{2} \mathrm{O}\) are present in a \(12.6 \mathrm{~g}\) sample of the compound?

A) \(1.72 \times 10^{23}\) molecules

B) \(7.59 \times 10^{24}\) molecules

C) \(5.14 \times 10^{23}\) molecules

D) \(1.289\) molecules

E) \(3.34 \times 10^{26}\) molecules

28) When the equation below is balanced with the lowest possible whole number coefficients, what is the sum of the coefficients?

$$ \mathrm{Ca}(s)+\mathrm{HCl}(g) \rightarrow \mathrm{CaCl}_{2}(s)+\mathrm{H}_{2}(g) $$

C) 4

D) 2

E) 8

29) Lithium oxide can be produced by the reaction shown below. If a manufacturing company wants to make \(25.0 \mathrm{~g}\) of \(\mathrm{Li}_{2} \mathrm{O}\), what mass of \(\mathrm{Li}\) is necessary? [Molar masses: \(\mathrm{Li}, 6.94 \mathrm{~g} / \mathrm{mol} ; \mathrm{O}, 16.00 \mathrm{~g} / \mathrm{mol}]\)

\(4 \mathrm{Li}(s)+\mathrm{O}_{2}(g) \rightarrow 2 \mathrm{Li}_{2} \mathrm{O}(s)\)

A) \(12.5 \mathrm{~g} \mathrm{Li}\)

B) \(2.903 \mathrm{~g} \mathrm{Li}\)

C) \(23.2 \mathrm{~g} \mathrm{Li}\)

D) \(11.6 \mathrm{~g} \mathrm{Li}\)

E) \(0.0861 \mathrm{~g} \mathrm{Li}\)

30) Magnesium hydroxide, \(\mathrm{Mg}(\mathrm{OH})_{2}\), as "Milk of Magnesia" can be used to neutralize excess stomach acid, represented by \(\mathrm{HCl}(a q)\) according to the chemical equation below.

$$ \mathrm{Mg}(\mathrm{OH})_{2}(s)+2 \mathrm{HCl}(a q) \rightarrow \mathrm{MgCl}_{2}(a q)+2 \mathrm{H}_{2} \mathrm{O}(\ell) $$

When \(5.00 \mathrm{~g}\) of \(\mathrm{HCl}\) are combined with an excess of \(\mathrm{Mg}(\mathrm{OH})_{2}\), what mass of \(\mathrm{MgCl}_{2}\) can be produced? [Molar masses: H, \(1.01 \mathrm{~g} / \mathrm{mol} ; \mathrm{O}, 16.00 \mathrm{~g} / \mathrm{mol} ; \mathrm{Mg}, 24.31 \mathrm{~g} / \mathrm{mol} ; \mathrm{Cl}\),

\(35.45 \mathrm{~g} / \mathrm{mol}]\)

A) \(2.50 \mathrm{~g}\)

B) \(0.957 \mathrm{~g}\)

C) \(13.1 \mathrm{~g}\)

D) \(70.5 \mathrm{~g}\)

E) \(6.53 \mathrm{~g}\)

Answer 1