Atoms and Molecules

1

What is the atomic number of oxygen?

A 8 B 16 C 6 D 10

2

Which of the following is a molecule?

A Na B O2 C NaCl D Both B and C

3

Who proposed the atomic theory?

A John Dalton B J.J. Thomson C Ernest Rutherford D Niels Bohr

4

What is an ion?

A A neutral atom B A charged atom or molecule C A molecule with no charge D A type of element

5

What is the mass number of an atom with 6 protons and 6 neutrons?

A 6 B 12 C 18 D 24

6

What is a cation?

A A positively charged ion B A negatively charged ion C A neutral ion D A molecule

7

What is the chemical formula of ammonia?

A CH4 B CO2 C H2O D NH3

8

Which of the following is a covalent compound?

A NaCl B KCl C H2O D MgO

9

Which of the following is a molecular element?

A Na B O2 C NaCl D CO2

10

Which of the following is an ionic compound?

A H2O B CO2 C NaCl D CH4

11

What is an atom?

A The smallest particle of an element that retains its properties B A group of elements chemically combined C A mixture of different substances D A large particle of matter

12

What is a molecule?

A The smallest particle of an element B Two or more atoms chemically bonded together C A mixture of elements D A single atom

13

How many protons are in a neutral atom of oxygen (atomic number 8)?

A 6 B 8 C 16 D 10

14

What is the valency of hydrogen?

A 1 B 2 C 3 D 4

15

Which of the following is NOT a molecule?

A H2 B O2 C Na D CO2

16

What is the atomic number of an atom?

A The total number of protons B The total number of neutrons C The total number of electrons D The total mass of the atom

17

What is the law of constant proportions?

A Elements combine in fixed ratios by mass B Elements combine in variable ratios C Compounds can be separated easily D Atoms are indivisible

18

What is the chemical formula of sodium chloride?

A H2O B CO2 C NaCl D CH4

19

Which of the following is a noble gas?

A Oxygen B Helium C Nitrogen D Hydrogen

20

What is the chemical formula of water?

A H2O B CO2 C NaCl D CH4

21

Which of the following is an example of a compound?

A Oxygen gas B Water C Air D Gold

22

What is the mass number of an atom with 8 protons and 8 neutrons?

A 8 B 16 C 24 D 32

23

What is the difference between an atom and a molecule?

A An atom is the smallest unit of an element; a molecule is made of two or more atoms B An atom is larger than a molecule C A molecule is the smallest unit of an element D There is no difference

24

What is an anion?

A A positively charged ion B A negatively charged ion C A neutral ion D An atom with no charge

25

How many electrons are in a neutral atom of hydrogen?

A 0 B 1 C 2 D 3