### How many formula units are in a sample of rust, Fe2O3 that has a mass of

How many formula units are in a sample of rust, Fe_{2}O_{3}, that has a mass of 5.0 g?

A) 1.9 ? 10^{25} B) 0.031 C) 1.9 ? 10^{22} D) 0.070 E) 4.2 ? 10^{22}

62. How many molecules are in a sample of water, H_{2}O, that has a mass of 50.0 g?

A)1.67 ? 10^{24} moleculesD)3.01 ? 10^{25} molecules

B)5.42 ? 10^{26} moleculesE)8.30 ? 10^{–23} molecules

C)2.16 ? 10^{23} molecules

63. How many formula units are in a sample of NaCl that has a mass of 175 g?

A)2.01 ? 10^{23} formula unitsD)1.05 ? 10^{26} formula units

B)1.80 ? 10^{24} formula unitsE)2.91 ? 10^{–22} formula units

C)6.16 ? 10^{27} formula units

64. How many moles are in a sample of ethanol, CH_{3}CH_{2}OH, that has a volume of 100.0 mL? The molar mass and density of ethanol are 46.07 g/mol and 0.789 g/mL, respectively.

A) 78.9 mol B) 1.71 mol C) 36.3 mol D) 2.75 mol E) 0.504 mol

65. How many moles are in a sample of ethylene glycol (commonly found in antifreeze), HOCH_{2}CH_{2}OH, that has a volume of 250.0 mL? The molar mass and density of ethylene glycol are 62.07 g/mol and 1.11 g/mL, respectively.

A)4.47 molD)1.40 ? 10^{4} mol

B)0.276 molE)1.72 ? 10^{4} mol

C)3.63 mol

66. How many oxygen atoms are in 75.0 g of SO_{3}?

A)225 atomsD)1.69 ? 10^{24} atoms

B)0.937 atomsE)4.52 ? 10^{25} atoms

C)5.64 ? 10^{23} atoms

67. How many hydrogen atoms are in 135 g of H_{2}O?

A)170 atomsD)8.04 ? 10^{22} atoms

B)4.51 ? 10^{24} atomsE)2.49 ? 10^{–23} atoms

C)9.02 ? 10^{24} atoms

68. How many sodium ions are in 125 g of Na_{2}SO_{4}?

A)1.06 ? 10^{24} atomsD)1.37 ? 10^{24} atoms

B)5.30 ? 10^{23} atomsE)1.46 ? 10^{–24} atoms

C)6.84 ? 10^{23} atoms

69. How many nitrate ions are in 75.0 g of Zn(NO_{3})_{2}?

A)0.396 atomsD)4.77 ? 10^{23} atoms

B)0.792 atomsE)6.57 ? 10^{–25} atoms

C)2.38 ? 10^{23} atoms

70. Rank the following compounds in order from least nitrogen atoms to most nitrogen atoms in a 50.0 g sample: N_{2}, N_{2}O_{5}, NH_{3}, NH_{4}Cl

A)N_{2 }_{2}O_{5 }_{3 }_{4}ClD)NH_{3 }_{4}Cl _{2 }_{2}O_{5}

B)N_{2}O_{5 }_{4}Cl _{3 }_{2}E)NH_{4}Cl _{3 }_{2 }_{2}O_{5}

C)N_{2 }_{3 }_{4}Cl _{2}O_{5}

abhinav behal
15-Feb-2020