Materials Around Us

Before dropping a big wooden log and a small iron nail into the village pond, Tara says the log will float and the nail will sink. Her cousin Advait says it will be the other way round — the log is far heavier than the nail, so the log will sink and the light little nail will float. Whose prediction will come true?

The bathroom window in Parth's house has frosted glass. Parth says the glass is opaque, because you can't see anything clearly through it. Mitali says it isn't opaque — it's translucent. Who has it right?

Lavanya's grandmother has an old copper lota that has turned dull and brownish-black. Lavanya says copper is still a lustrous material — the shine is just hidden under a dull layer. Hamid says lustrous means shiny, and this lota is clearly not shiny, so this copper is not lustrous. Whose reasoning holds up?

Charu stirs a spoonful of salt into a glass of water until the water looks perfectly clear again. Charu says the salt is gone — it has vanished. Her classmate Bhuvan says the salt is still in the glass, even though no one can see it. Which of them should the class believe?

Nupur wants to find out which is harder: a big candle or a small iron key. She says the fair test is to try scratching each one with the other. Pranav says there's no need — just weigh them; the big candle is heavier, so it must be harder. Who is thinking about it correctly?

Jasleen notices that the frying pan at home is made of metal, but its handle is made of hard plastic. Jasleen says the handle is plastic only because plastic is cheaper — a metal handle would be better, since metal is stronger. Esha says the handle is made of a different material because the handle has a different job from the pan. Whose explanation is correct?