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HOLY CHILD SCHOOL

B. Labao St. Ext., Iligan City

FOURTH PRELIMINARY EXAMINATION

SCIENCE : Chemistry

Name: _______________________________________________________________________________ Date: _____________________________________

Teacher: _____________________________________________________________________________ Score: ____________________________________

I. MODIFIED TRUE/FALSE. Write the word TRUE if it tells a truth or underline the word/words that make thestatement false and place the correct answer on the space provided. (2pts each)

_____________________________ 1. Chemical equations do not come already imbalanced.

_____________________________ 2. A balanced equation has unequal numbers of each type of atom on each side of

the equation.

_____________________________ 3. When balancing an equation, you cannot change a subscript.

_____________________________ 4. You cannot place a coefficient in the middle of a formula.

_____________________________ 5. Make sure that your final set of coefficients is all whole numbers with no

common factors other than one._____________________________ 6. When sodium metal (Na) and a chlorine gas (CL2) react, the product is the

organic compound NaCl.

_____________________________ 7.

Sometimes, in balancing equations, fractional coefficient seems necessary.

_____________________________ 8. Decomposition reactions occur between two or more different elements._____________________________ 9. The products of chemical reaction are identified by doing experiments.

_____________________________ 10. Substances other than carbons will burn in oxygen.

II. IDENTIFICATION. Recognize the answers and place it on the space provided._____________________________ 1. The notation using symbols and numerals to represent the composition of

substances

_____________________________ 2. The major component of natural gas._____________________________ 3. This is used in wielding torches.

_____________________________ 4. This is a component of gasoline.

_____________________________ 5. A compound breaks down to form two or more simpler substances.

_____________________________ 6. This is a combination of two or more substance to form a compound.

_____________________________ 7. This is the common name for combustion.

_____________________________ 8. The energy released

_____________________________ 9. by combustion

_____________________________ 10. This is an exothermic reaction in which a substance combines with oxygen

forming products in which all elements are combined with oxygen.

_____________________________ 11. This is a starting substance in a chemical reaction.

_____________________________ 12. A substance produced as result of a chemical change._____________________________ 13. The general form of synthesis reactions

_____________________________ 14. The general form of decomposition reactions

_____________________________ 15. This is a compound containing only the elements hydrogen and carbon.

III.ENUMERATION. List the items needed to each number.A. 4 Steps in Writing and Balancing Chemical EquationsB. 5 Examples of Hydrocarbons

C. 6 Examples of that may undergo Combustion

IV. PROBLEM SOLVING . Solve the following problems.

A. Balance the following equation.

1. __ SnO2 + __ H2 __ Sn + __ H2O

2. __ KOH + __ H3PO4 __ K3PO4 + __ H2O

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3. __ KNO3 + __ H2CO3 __ K2CO3 + __ HNO34. __ Na3PO4 + __ HCl __ NaCl + __ H3PO45. __ TiCl4 + __ H2O __ TiO2 + __ HCl6. __ C2H6O + __ O2 __ CO2 + __ H2O7. __ NH3 + __ O2 __ NO + __ H2O8. __ AgI + __ Na2S __ Ag2S + __ NaI9. __ FeS + __ O2 __ Fe2O3 + __ SO210.__ PCl5 + __ H2O __ H3PO4 + __ HCl

B. Give the products of the following chemical reactions.

1. C + O2 _____________ 4. 2Sb + 3I2 _____________

2. 2H2 + O2 _____________ 5. 2Na + Cl2 _____________

3. 4Fe + 3O2 _____________

V. ESSAY. Explain the questions briefly.A. What is balancing chemical equations? (5 points)

B. What is combustion reactions? (5 points)

C. What is the difference between synthesis and decomposition reactions? (5 points)