Choose the best answer and write the letter of to the air c. It will tasto sweet. d. It will turn into brown. 2. What will be formed on nails or metals when exposed to oxygen? DDS Dhe c. molds d. rust 3. A house is buming and the wind blows hard. Fire increases rapidly. This is due to lack of oxygen c. presence of fire extinguisher presence of oxygen d. the use of water to stop the fire 4 Which of the following situations show the effect of lack of oxygen on material? 2. sporting of food c. decaying of dead organisms rusting of iron d. burning wick placed inside a closed jar 5. This is also known as the duming process, and it is supported by oxygen. a combustion h chemical change c. decomposition d. physical change 6. By keeping the food cooled the growth of microorganisms are a. increased b. minimized c. not changed d. stopped and they are killed 7 Which of the following is true about bacteria? a. Bacteria grows faster in warm environments. . Bacteria needs air to survive. c. Every type of bacteria can cause food poisoning. d. d. By freezing food you can kill the bacteria. & in which place will rusting of iron occur easily? a. humid place c. dry place b. dusty place d. shady place 9. When metal rusts, the material that is rusting becomes a. Hard c. strong b. Soft d. sturdy 10. Which is true about chemical change? a. A new material is formed. b. The product cannot be changed to its original form. C. The product is improved and becomes durable. d. Both a and b are correct.​