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IMU CET Composition of Substances and Solutions — practice questions — page 2

Explore 91 free Composition of Substances and Solutions questions in IMU CET Chemistry. Open each question or exercise to read its content, reference answers and available explanation.

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Composition of Substances and Solutions questions and exercises with answers

Showing questions 31–60 of 91.

The daily allowance of vitamin C for children aged four to eight is 1.42 x 10^-4 mol. If its molar mass is 176.124 g/mol, what mass is this?Read the answer and worked solution →A 40.0 mg packet of saccharin, C7H5NO3S, has a molar mass of 183.18 g/mol. How many saccharin molecules does it hold?Read the answer and worked solution →A saccharin sample contains 1.31 x 10^20 molecules of C7H5NO3S. How many carbon atoms are present?Read the answer and worked solution →How many hydrogen atoms are in 9.213 g of C4H10, which contains 9.545 x 10^22 molecules?Read the answer and worked solution →Roughly what mass does one mole of water molecules have?Read the answer and worked solution →Vesicles in one type of mouse brain neuron hold about how many dopamine molecules on average?Read the answer and worked solution →A 10.0 g sample of a gas contains 2.5 g of hydrogen and 7.5 g of carbon. What is its percent composition?Read the answer and worked solution →A 12.04 g liquid sample contains 7.34 g of carbon. What is the mass percentage of carbon?Read the answer and worked solution →The same 12.04 g sample holds 1.85 g of hydrogen and 2.85 g of nitrogen. What is the mass percentage of nitrogen?Read the answer and worked solution →A 24.81 g gaseous sample contains 3.01 g C, 4.00 g O and 17.81 g Cl. What is the mass percentage of chlorine?Read the answer and worked solution →Ammonia has a formula mass of 17.03 amu, with one nitrogen atom of 14.01 amu. What is the mass percentage of nitrogen in NH3?Read the answer and worked solution →Aspirin is C9H8O4 with a molar mass of 180.159 g/mol. Using C = 12.01 g/mol, what is its mass percentage of carbon?Read the answer and worked solution →For aspirin, C9H8O4, with molar mass 180.159 g/mol and O = 16.00 g/mol, what is the mass percentage of oxygen?Read the answer and worked solution →What is the mass percentage of iron in Fe2O3, to three significant figures, using Fe = 55.85 and O = 16.00 g/mol?Read the answer and worked solution →A tentative empirical formula works out as ClO3.5. What is the correct empirical formula?Read the answer and worked solution →A hematite sample holds 34.97 g of iron. Using Fe = 55.85 g/mol, how many moles of iron is this?Read the answer and worked solution →A hematite sample contains 34.97 g of iron and 15.03 g of oxygen. What is its empirical formula, given Fe = 55.85 and O = 16.00 g/mol?Read the answer and worked solution →A compound contains 0.130 g of nitrogen and 0.370 g of oxygen. What is its empirical formula, using N = 14.007 and O = 16.00 g/mol?Read the answer and worked solution →A gas is 27.29% C and 72.71% O by mass. What is its empirical formula, using C = 12.01 and O = 16.00 g/mol?Read the answer and worked solution →A compound is 40.0% C, 6.71% H and 53.28% O by mass. What is its empirical formula?Read the answer and worked solution →Besides the empirical formula, what is needed to work out a compound's molecular formula?Read the answer and worked solution →A 40.57 g sample of nicotine is found to be 0.2500 mol. What is the molar mass of nicotine?Read the answer and worked solution →What makes a solution a homogeneous mixture?Read the answer and worked solution →What is a solute?Read the answer and worked solution →What name is given to a solution in which water is the solvent?Read the answer and worked solution →How is molarity defined?Read the answer and worked solution →A 355 mL soft drink sample contains 0.133 mol of sucrose. What is the molar concentration of sucrose?Read the answer and worked solution →A teaspoon holding about 0.01 mol of sucrose is stirred into 200 mL of tea. What is the molarity of sucrose?Read the answer and worked solution →How many moles of sugar are in a 10 mL sip of a soft drink whose sucrose concentration is 0.375 M?Read the answer and worked solution →A 0.500 L vinegar solution contains 25.2 g of acetic acid, molar mass 60.052 g/mol. What is its molarity?Read the answer and worked solution →

Worked practice questions

The daily allowance of vitamin C for children aged four to eight is 1.42 x 10^-4 mol. If its molar mass is 176.124 g/mol, what mass is this?

  1. 0.0250 g
  2. 0.250 g
  3. 0.00806 g
  4. 0.0125 g
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Correct answer: A. 0.0250 g

1. Mass is obtained by multiplying the amount in moles by the molar mass. 2. That gives 1.42 x 10^-4 mol x 176.124 g/mol. 3. The product is 0.0250 g of vitamin C. 4. As a check, one ten thousandth of a mole should weigh roughly one ten thousandth of 176 g, near 0.02 g. 5. The value 0.00806 g comes from dividing by the molar mass rather than multiplying by it. _Source: OpenStax Chemistry (CC BY 4.0), Ch 3 "Composition of Substances and Solutions", section 3.1 Formula Mass and the Mole Concept_

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A 40.0 mg packet of saccharin, C7H5NO3S, has a molar mass of 183.18 g/mol. How many saccharin molecules does it hold?

  1. 1.31 x 10^23 molecules
  2. 1.31 x 10^20 molecules
  3. 2.19 x 10^20 molecules
  4. 9.17 x 10^20 molecules
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Correct answer: B. 1.31 x 10^20 molecules

1. Convert the mass to grams first: 40.0 mg = 0.0400 g. 2. Find the amount in moles: 0.0400 g / 183.18 g/mol = 2.184 x 10^-4 mol. 3. Multiply by Avogadro's number: 2.184 x 10^-4 mol x 6.022 x 10^23 molecules/mol. 4. The product is 1.31 x 10^20 saccharin molecules. 5. Units cancel, since grams go in step two and moles go in step three. 6. The value 2.19 x 10^20 stops at the mole count and never applies Avogadro's number properly. 7. The value 9.17 x 10^20 is the count of carbon atoms, not of whole molecules. _Source: OpenStax Chemistry (CC BY 4.0), Ch 3 "Composition of Substances and Solutions", section 3.1 Formula Mass and the Mole Concept_

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A saccharin sample contains 1.31 x 10^20 molecules of C7H5NO3S. How many carbon atoms are present?

  1. 1.31 x 10^20 atoms
  2. 6.55 x 10^20 atoms
  3. 9.17 x 10^20 atoms
  4. 1.87 x 10^19 atoms
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Correct answer: C. 9.17 x 10^20 atoms

1. The subscript on carbon in C7H5NO3S shows seven carbon atoms in every molecule. 2. Multiply the molecule count by seven: 1.31 x 10^20 x 7. 3. The product is 9.17 x 10^20 carbon atoms. 4. The value 6.55 x 10^20 uses the five hydrogen atoms instead of the seven carbon atoms. 5. Dividing by seven instead of multiplying gives 1.87 x 10^19, which is smaller than the molecule count and so cannot be right. _Source: OpenStax Chemistry (CC BY 4.0), Ch 3 "Composition of Substances and Solutions", section 3.1 Formula Mass and the Mole Concept_

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