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MCQ practice · SSC Physics Board questions · Chapter 5: State of Matter and Pressure

Mymensingh Board 2023

What will happen if an object of mass 200 g and volume 250 cm³ is released in water?

Think it through first, then pick an option.

  1. a The object will sink
  2. b 80% of the object will remain submerged
  3. c The object will float fully immersed
  4. d 50% of the object will remain submerged
Answer and explanation

Correct answer: b 80% of the object will remain submerged

The density is 0.8 gm/cc, so when floating the submerged part is 0.8 ÷ 1 × 100 = 80%.

Why the other options are wrong

  • a The object will sink: To sink the density must exceed that of water; here it is 200 ÷ 250 = 0.8 gm/cc, less than water.
  • c The object will float fully immersed: To float fully immersed the density would have to equal water, 1 gm/cc; here it is 0.8.
  • d 50% of the object will remain submerged: To be 50% submerged the density would have to be 0.5 gm/cc; here it is 0.8 gm/cc.