2. Atoms & Elements

Mole Concept

Multiple Choice
How many moles of hydrogen atoms are present in 135 mg of H_2O?
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Multiple Choice
How many atoms of hydrogen (H) are present in 200 molecules of ammonia (NH_3)?
Multiple Choice
How many particles are present in one mole of a substance?
Multiple Choice
How many moles of KI are required to prepare 0.50 L of a 0.20 M aqueous solution?
Multiple Choice
In general chemistry, what does one mole represent?
Multiple Choice
How many moles of Pb are present in 4.71 × 10^{21} Pb atoms?
Open Question
The number of moles of hydrogen that is needed to produce 0.253 mol of water is
Open Question
How many moles are there in 8.50 x 10^24 molecules of sodium sulfate, Na₂SO₃?
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Open Question
How many sodium ions are contained in 99.6 mg of Na₂SO₃
Multiple Choice
A compound containing only carbon and hydrogen has a carbon-to-hydrogen mass ratio of 11.89. Which of the following carbon-to-hydrogen mass ratios is possible for another compound composed only of carbon and hydrogen?
Open Question
What is the mass of 3.8 × 10²⁴ atoms of argon (Ar)?
Multiple Choice
A solution is prepared by dissolving 20.2 mL of methanol (CH3OH) in 100.0 mL of water at 25°C. The final volume of the solution is 118 mL. The densities of methanol and water at this temperature are 0.782 g/mL and 1.00 g/mL, respectively. For this solution, what is the concentration of methanol in terms of molarity?
Open Question
How many atoms of nitrogen are in the chemical formula Ni(NO₃)₂? 2 1 6 3
Multiple Choice
Based on the data provided in Table 1, which item contains the largest quantity of moles?
Multiple Choice
Which of the following samples contains the greatest number of atoms?