Q: Which of the following is the correct relationship for the number of neutrons in an atom?

$$\text{Number of neutrons} = A - Z$$

Question 1

Which statement best describes the Law of Definite Proportions?

Accepted Answer

All samples of a given compound, regardless of their source or preparation, have the same proportions of their constituent elements.

Question 2

A student measures the mass of a beaker before and after a chemical reaction and finds the mass is unchanged. Which law does this observation support?

Accepted Answer

Law of Conservation of Mass

Question 3

Which of the following is a correct conversion of 3.409 mi/hr to km/min? (Use $$1 	ext{ mi} = 1.60934 	ext{ km}$$ and $$1 	ext{ hr} = 60 	ext{ min})$$

Accepted Answer

$$0.09143 	ext{ km/min}$$

Question 4

Which of the following statements about isotopes is TRUE?

Accepted Answer

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

Question 5

A sample of pure neon contains three isotopes: $$^{20}	ext{Ne} (90.48$$%), $$^{21}	ext{Ne} (0.27$$%), and $$^{22}	ext{Ne} (9.25$$%). What is the weighted average atomic mass of neon? (Isotopic masses: $$^{20}	ext{Ne} = 19.9924 $$amu, $$^{21}	ext{Ne} = 20.9938 $$amu, $$^{22}	ext{Ne} = 21.9914 $$amu)

Accepted Answer

$$20.18 	ext{ amu}$$

Question 6

Which subatomic particle was discovered using cathode ray tube experiments?

Accepted Answer

Electron

Question 7

Which of the following is NOT a molecular compound?

Accepted Answer

NaCl

Question 8

What is the charge and classification of a sulfur ion that has gained two electrons?

Accepted Answer

Charge is $$-2$$ and it is called an anion.

Question 9

Which of the following ions is a polyatomic ion?

Accepted Answer

$$	ext{NO}_3^- ($$nitrate)

Question 10

Which of the following elements is defined by having 6 protons in its nucleus?

Accepted Answer

Carbon

Question 11

Which of the following compounds is named correctly?

Accepted Answer

Na$$_3PO$_4$$; sodium phosphate

Question 12

Which statement about the atomic nucleus is correct according to Rutherford's nuclear model?

Accepted Answer

Most of the atom's mass and all of its positive charge are contained in a small core called the nucleus.

Question 13

Which of the following is the empirical formula for hydrogen peroxide?

Accepted Answer

HO

Question 14

If an atom has 17 protons, 18 neutrons, and 17 electrons, what is its mass number?

Accepted Answer

$$35$$

Question 15

Which of the following ions is isoelectronic with neon ($$	ext{Ne}$$)?

Accepted Answer

$$	ext{Na}^+$$

Question 16

Which of the following is the correct formula for calcium carbonate?

Accepted Answer

CaCO$$_3$$

Question 17

Which statement about the periodic table is TRUE?

Accepted Answer

Elements are arranged in order of increasing atomic number.

Question 18

Which of the following ions has a predictable charge based on its group number?

Accepted Answer

$$	ext{Mg}^{2+}$$

Question 19

Which of the following is the correct relationship for the number of neutrons in an atom?

Accepted Answer

$$	ext{Number of neutrons} = A - Z$$

Question 20

A stable element has two isotopes with masses 10.0129 amu and 11.0093 amu. The atomic mass is 10.81 amu. Which isotope is more abundant?

Accepted Answer

The isotope with a mass of 11.0093 amu is more abundant.

General Chemistry Fundamentals: Units, Atomic Theory, and Classification of Matter

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