You will hear a recording. Select the paragraph that best relates to the recording.

(1) The hardest mineral is determined by the Mohs Scale of Hardness. The diamonds are close to glass in hardness, and Gypsum is known as the softest substance on Mohs.

(2) Friedrich Mohs was the first person to realize how hard diamonds are. The professor tells the students to look in their textbooks so that they can learn about the hardness of them.

(3) Mohs Scale of Hardness is created to rate minerals. Hardness refers to a material’s ability to scratch the other objects and different materials are received different rank on this scale.

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