Q: A sample of glucose ($$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6) $$contains $$0.250$$ moles. How many molecules of glucose are present?

$$1.51 \times 10$$^{23}$$ molecules

Question 1

Which of the following statements best distinguishes between a hypothesis and a scientific theory?

Accepted Answer

A hypothesis is a tentative explanation that can be tested, while a scientific theory is a well-substantiated explanation based on a body of evidence.

Question 2

A sample of matter is uniform throughout and can be separated into two substances by a physical process. Which classification best describes this sample?

Accepted Answer

Homogeneous mixture

Question 3

Which of the following is a chemical change?

Accepted Answer

Iron rusting in moist air

Question 4

A student measures the mass of a sample three times and gets values that are very close to each other, but far from the true value. This set of measurements is:

Accepted Answer

Precise but not accurate

Question 5

Convert $$25.0 \, ^\circ \mathrm{C} to $$Kelvin.

Accepted Answer

$$298.2 \, \mathrm{K}$$

Question 6

Which of the following best describes the law of definite proportions?

Accepted Answer

A chemical compound always contains the same elements in the same proportion by mass.

Question 7

Which experiment provided the first evidence for the existence of the electron?

Accepted Answer

J. J. Thomson's cathode ray tube experiment

Question 8

An atom has 17 protons, 18 neutrons, and 17 electrons. What is its chemical symbol and mass number?

Accepted Answer

$$^{35}\mathrm{Cl}$$

Question 9

Which of the following elements is a metalloid?

Accepted Answer

Silicon

Question 10

How many moles are in $$3.01 	imes 10$$^{23}$$ molecules of water ($$\mathrm{H}_2\mathrm{O}$$)?

Accepted Answer

$$0.500$$ moles

Question 11

Which of the following best describes an ionic compound?

Accepted Answer

A compound composed of cations and anions held together by electrostatic forces

Question 12

What is the empirical formula of a compound that contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass?

Accepted Answer

$$\mathrm{CH}_2\mathrm{O}$$

Question 13

Which of the following is a correct name for the compound $$\mathrm{Na}_2\mathrm{SO}_4$$?

Accepted Answer

Sodium sulfate

Question 14

A sample of glucose ($$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6) $$contains $$0.250$$ moles. How many molecules of glucose are present?

Accepted Answer

$$1.51 	imes 10$$^{23}$$ molecules

Question 15

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 16

Which of the following is the correct formula for dinitrogen pentoxide?

Accepted Answer

$$\mathrm{N}_2\mathrm{O}_5$$

Question 17

Which of the following is a physical property?

Accepted Answer

Boiling point

Question 18

A compound contains only carbon and hydrogen. Combustion of $$0.100 g of $$the compound produces $$0.344 g of$$ $$\mathrm{CO}_2$$ and $$0.141 g of$$ $$\mathrm{H}_2\mathrm{O}. $$What is the empirical formula of the compound?

Accepted Answer

$$\mathrm{CH}_2$$

Question 19

Which of the following is a correct statement about Avogadro's number?

Accepted Answer

It is the number of particles in one mole of a substance.

Question 20

Which of the following best explains why noble gases are generally unreactive?

Accepted Answer

They have completely filled valence electron shells.

General Chemistry I: Study Guide – Matter, Measurement, Atoms, and Compounds

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