$$6.022 \times 10$$^{23}$$, the number of entities in one mole of a substance

$$\text{Density} = \frac{\text{Mass}}{\text{Volume}}$$

Charge: $$-1$$, Mass: $$1/1837 \text{ u}$$

Question 1

Which scientific law states that during a chemical change, matter is neither created nor destroyed?

Accepted Answer

Law of Conservation of Mass

Question 2

A sample of water weighing 85.0 g is decomposed to produce 75.5 g of oxygen. What is the mass of hydrogen produced?

Accepted Answer

9.5 g

Question 3

Which statement best describes the Law of Definite Proportions?

Accepted Answer

A compound always contains the same elements in the same ratio by mass, regardless of its source.

Question 4

What is Avogadro's number, and what does it represent?

Accepted Answer

$$6.022 	imes 10$$^{23}$$, the number of entities in one mole of a substance

Question 5

Calculate the number of moles of $$CO_2 in a 150.0 g $$sample. (Molar mass of $$CO_2 is$$ $$44.0 g/$$mol)

Accepted Answer

3.41 moles

Question 6

Which subatomic particle has a mass of approximately $$1 	ext{ u}$$ and a charge of $$+1$$?

Accepted Answer

Proton

Question 7

What is the atomic number and mass number of silicon ($$Si) as $$shown in the periodic table?

Accepted Answer

Atomic number: 14, Mass number: 28.085

Question 8

Which of the following best describes an isotope?

Accepted Answer

Atoms with the same number of protons but different numbers of neutrons

Question 9

What is the nuclear symbol for an oxygen isotope with 8 protons and 10 neutrons?

Accepted Answer

$$^{18}_{8}O$$

Question 10

Which type of radioactive decay involves a neutron turning into a proton and emitting an electron?

Accepted Answer

Beta decay

Question 11

If carbon-14 undergoes beta decay, what element does it become?

Accepted Answer

Nitrogen-14

Question 12

Which of the following is a cation?

Accepted Answer

An atom that has lost electrons

Question 13

What is the formula for density?

Accepted Answer

$$	ext{Density} = \frac{	ext{Mass}}{	ext{Volume}}$$

Question 14

Which of the following is true about the molar mass of water ($$H_2O$$)?

Accepted Answer

It is the sum of the atomic masses of hydrogen and oxygen.

Question 15

Which particle is found outside the nucleus and has a negative charge?

Accepted Answer

Electron

Question 16

A box of rocks is less dense than a box of leaves of the same size. Which statement is most reasonable?

Accepted Answer

Leaves have less mass per unit volume than rocks.

Question 17

Which of the following is NOT a subatomic particle?

Accepted Answer

Molecule

Question 18

What is the charge and mass of a beta particle?

Accepted Answer

Charge: $$-1$$, Mass: $$1/1837 	ext{ u}$$

Question 19

Which process is responsible for ocean acidification as shown in the diagram?

Accepted Answer

Carbon dioxide reacts with water to form carbonic acid, which releases hydrogen ions.

Question 20

What is the half-life of a radioactive isotope?

Accepted Answer

The time it takes for half of the radioactive atoms to decay into a different isotope.

Atomic Structure, Moles, and Scientific Laws: Introduction to Chemistry Study Notes

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