PRESENCE AND LACK OF OXYGEN

1.What change will happen to the slices of potato if they will be exposed to oxygen in the air?

• A.Color will change from brown to white

• B.Color will change from white to brown

• C.The color will not change

• D.No changes in color

2.What causes the rusting of iron nails or iron made materials in a wet cloth?

• A.presence of heat

• B. absence of heat

• C. presence of oxygen

• D. absence of oxygen

3. The candles melted by the application of heat. What change took place when solid candles became liquid?

• A. chemical

• B. mechanical

• C. no change

• D. physical

4. When the candle was lighted, it melted into liquid and became solid again after few seconds or in a minute. What causes these changes?

I. presence of heat

II. presence of oxygen

III. absence of heat

IV. absence of oxygen

• A. I, II and III

• B. I and IV

• C. I and II

• D. All of the above

5.what is the color of the apple/eggplant/potato after 48 hours?

• white

• lavander

• brownish

• green