Chemistry Practice Test 2 - Formulas

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1. A molecule of carbon dioxide has the chemical formula CO2. Which one of the statements below is true?
A) One carbon dioxide molecule is composed of one carbon atom and one oxygen atom. B) One carbon dioxide molecule is composed of two carbon atoms and two oxygen atoms. C) One carbon dioxide molecule is composed of four atoms. D) One carbon dioxide molecule is composed of three carbon atoms and six oxygen atoms. E) One carbon dioxide molecule is composed of one carbon atom and two oxygen atoms.

2. The compound known as aluminium sulfate has the chemical formula, Al2(SO4)3. Which one comment below is true?

A) For every 2 sulfur atoms present in aluminium sulfate, four oxygen atoms are also present. B) The chemical formula of aluminium sulfate(Al2(SO4)3)indicates the presence of one sulfur atom. C) The chemical formula of aluminium sulfate(Al2(SO4)3)indicates the presence of four oxygen atoms. D) For every two aluminium atoms present in aluminium sulfate, 12 oxygen atoms are present. E) One unit of aluminium sulfate(Al2(SO4)3) contains 13 atoms.

3. One molecule of sulfuric acid was examined and found to contain two hydrogen atoms, four oxygen atoms and one sulfur atom. Which option best represents the chemical formula for sulfuric acid?
A) HSO2 B) H2SO4 C) HSO D) H4S3O8 E) H3SO4

4. Look at the image of molecule "A" on the right. Which one of the formulae below best represents this molecule? The symbols for hydrogen and carbon are: Hydrogen = H; Carbon = C.
A) CH B) C2H6 C) CH3 D) C6H2 E) C2H2

5. A long molecule was found to have the semi-structural formula CH3CH2CH2COOH A structural formula gives the location of each atom in the molecule. Which one of the following formulae best represents this molecule? The symbols for oxygen, carbon and hydrogen are given below Hydrogen = H Oxygen = O Carbon = C.
A) C4O2H2 B) C2H6O2 C) C4H8O2 D) C3H6O E) C2H8O1

6. Look at the image of molecule "A" on the right. Which formula best represents this molecule? The chemical symbols for chlorine, oxygen, hydrogen and carbon are listed below. Oxygen = O Clorine = Cl Hydrogen = H Carbon = C
A) C3H5O B) C3H5Cl C) CHOCl D) C3H5OCl E) C2H2OCl

7. Aluminium forms ions with a charge of 3+(Al3+)while the carbonate ion(CO32-)has a charge of 2-. Which one of the following options represents the formula for aluminium carbonate.
A) Al(CO3)3 B) Al2(CO3)2 C) Al2(CO3)3 D) Al(CO3) E) Al3(CO3)2

8. Ammonium sulfate is a compound formed from the reaction between the ammonium ion(NH4+) and the sulfate ion (SO42-). Which of the following options represents the formula for ammonium sulfate?
A) (NH4)SO4 B) (NH4)2SO4 C) (NH4)2(SO4)2 D) NH4(SO4) 2 E) None of the above represent the formula

9. The neutral atom of element "X" has the electronic configuration 2,8,3. It reacts with element "Y" to produce a compound with the formula XY3. Which one of the comments below is true?
A) In the compound XY3, "Y" has a charge of +3 B) Atoms of element "X" produce ions with a charge of -3 while those of element "Y" also produce ions with a charge of -3. C) Atoms of element "X" produce ions with a charge of +3 while those of element "Y" produce ions with a charge of -1. D) In the compound XY3, "X" has a charge of -3 E) None of the above are true.

10. Magnesium forms ions with a charge of 2+ (Mg2+)while the carbonate ion has a charge of 2- (CO32-). Which one of the following options represents the formula for magnesium carbonate?
A) (CO3)3Mg B) CO3Mg2 C) Mg(CO3)2 D) MgCO3 E) Mg3CO3

11. Lead forms ions with a charge of 2+ (Pb2+). When lead reacts with element "X" a compound is formed with the formula Pb3X2. Element "X" also reacts with lithium ions (Li+). What is the likely formula of the compound formed between lithium and element "X".
A) Li3X B) X3Li C) Li2X D) LiX E) Li3X2

12. Which one of the following options represents the chemical formula for sodium carbonate?
A) Na(CO3)3 B) Na3CO3 C) Na2CO3 D) NaCO3 E) Na2(CO3)3

13. Which one of the following options represents the chemical formula for lead(II)sulfate?
A) Pb(SO4)3 B) Pb3(SO4)2 C) Pb(SO4)2 D) Pb2SO4 E) PbSO4

14. What is the formula for ammonium phosphate? Phosphate = PO43- Ammonium - NH4+
A) (NH4)3PO4 B) NH12PO4 C) (NH4)3(PO4)1 D) (NH4)(PO4) E) (NH4)2PO4

15. Ammonium phosphate((NH4)3PO4) is used as a fertiliser in the farming industry. How many atoms of hydrogen are present in the smallest particle of ammonium phosphate?
A) 6 B) 9 C) 12 D) 4 E) 8

16. Octane is used as a fuel for cars. It has the formula CH3(CH2)6CH3. How many hydrogen atoms are present in every molecule of octane?
A) 16 B) 4 C) 12 D) 8 E) 18

17. Consider the particle shown on the right. Each different coloured circle represents a different type of atom. Which of the following options best identifies the particle. red =R, yellow = Y, blue = B
A) B2RY2 B) BYR C) 2B2YR D) 2BY2R E) B2Y2R

18. Consider the particle shown on the right. Each different coloured circle represents a different type of atom. Which of the following options best identifies the particle. red =R, yellow = Y, blue = B
A) B2R2Y B) B2RY C) BRY D) YRB2 E) 2BRY

19. Each coloured circle in the image represents a different atom. Which comment below best describes the image?
A) Element B) A mixture of compounds C) Compound D) A mixture of elements E) None of the above are true.

20. Look at the image on the right. It represents a chemical reaction. Which one comment below accurately describes the substances before and after the reaction?

A) A mixture of compounds exists before the reaction and a compound is present after the reaction. B) A mixture of elements exists before the reaction and a compound is present after the reaction. C) An element exists before the reaction and a compound is present after the reaction. D) A compound exists before the reaction and a compound is present after the reaction. E) None of the above are true