Cân bằng PTHH :
a. Na + Cl2 + ? -----------> ?
b. CxHyO2 + O2 -----------------> CO2 + H20
c. FeS2 + O2 -------------> ? + ?
d. NaOH + ? ---------------> NaCl + H2O
e. Fe(OH)3 ---------------> ? + ?
f. Fe + Cl2 ----------------> ?
g. e(OH)2 + O2 + H20 --------------> Fe(OH)3
h. Fe3O4 + Al --------------> Fe + CO2
i. FexOy + HCL ---------------> ? + H20
k. FexOy + CO --------> Fe + CO2
l. CnH_2n+2 + O2 ---------> CO2 + H2O

I. Choose the best answer to complete these sentences :
1. In the world , millions of old papers ...... away everyday.
a. thrown b. are throwing c. are thrown d. threw
2. Every milk bottle can be ...... thirty times.
a. recycled b. reused c. reduced d. returned
3. I am happy .............. all the exams.
a. passing b. to pass c. pass d. passed
4. She was very sad .........good marks in the final test.
a. not get b. not to get c. to not get d. not getting
5. It's ........................... to travel around Vietnam.
a. interesting b. interested c. interestingly d. interestedly
6. The ruler ........................ of plastic is Mai's .
a. making b. to make c. is made d. made
7. The man ..................... to the principal is my English teacher.
a. talks b. is talking c. talking d. to talk
8. Do you mind if I ................. the window ?
a. open b. to open c. opened d. opening
9. Would you mind .................... the washing up for me tonight ?
a. doing b. did c. to do d. done
10. Tim ................................ rice paddies beforea. never saw.
a. never saw b. never seen c. has never seen d. never to see

I. Underline the best answer to complete these sentences.
1. The boy (injuring/injured) in the accident was taken to the hospital.
2. The boy (swimming/swum) in the river is the fisher's son.
3. The window (breaking/broken) in the storm last night has been repaired.
4. The girl ( teaching/taught) English is Lan's sister.
5. The man (working/worked) in the garden is my grandfather.
6. The car (making/made) in Japan was very expensive.
7. The house (building/built) of wood belongs to my uncle.
8. The picture (taking/take) by his brother won the first prize in the art contest.
9. The girl (sitting/sat) next to me is intelligent.
10. The book (writing/written) by Mr Jones is about places of interest in Vietnam.