7. You have a 4 cm3 cube of BTB agar, and an 8 cms cube of BTB agar. Which one w

Question

7. You have a 4 cm3 cube of BTB agar, and an 8 cms cube of BTB agar. Which one would you expect to turn yellow first, when both are dropped into the same cup of vinegar at the same time? 8. It takes you 30 minutes to walk one mile - but your friend can walk the same distance in 15 minutes. Which of the following must be true? a. You are walking at a faster rate b. Your friend is walking at a faster rate c. You both are walking at the same rate d. Your friend is walking at a slower rate 9. In 5 minutes you can run half a mile. In the same 5 minutes, your friend can run 4 mile. Which of the following must be true? a. You are running at a faster rate b. Your friend is running at a faster rate c. You both are running at the same rate d. Your friend is running at a slower rate

Explanation / Answer

7.Correct answer would be: 4cm3

Reason: As the volume increases, the surface area to volume ratio decreases.It is through the surface that vinegar would diffuse to the cube.So, when surface area to volume ratio decreases,the time it will take for vinegar to diffuse throughout the volume of the cube will increase and this will happen in case of 8cm3 cube.Hence, 4cm3 cube will turn yellow fast.

8.Correct answer is:b.your friend is walking at a faster rate.

Reason:Since my friend covers the same distance earlier than me, it signifies that my friend runs at a faster rate than me.

9.Correct answer would be :b.your friend is running at a faster rate.

Reason: I cover 1/2 (say 2/4 )mile in 5 minutes and my friend covers 3/4 miles in 5 minutes.Clearly 3/4 is more than 2/4 .So, we can say that my friend is running at a faster rate.

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