Biology 9700 · AS & A Level · Movement into and out of cells

Movement into and out of cells — practice question

A pH indicator was used to dye some agar pink. From this pink agar, three agar cubes of different dimensions were cut. The cubes were then put into a beaker and covered with $0.1\,\text{mol dm}^{-3}$ hydrochloric acid. The experiment was kept at a constant temperature of $20^{\circ}\text{C}$. Hydrochloric acid diffused into the agar cubes, so the cubes lost their colour. Which agar cube, the one that became colourless in the shortest time, has the surface area to volume ratio?

  • A$0.33 : 1$
  • B$0.83 : 1$
  • C$1.2 : 1$
  • D$3.0 : 1$

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