Aknown compound has a melting point range of 134-137 degrees. you record a melting point range of 125-126 degrees celsius for a sample. is this sample a pure compound?

The sample for which melting point is being measured is not a pure sample.

It is observed that if a compound shows a lower temperature than the predicted melting point temperature / melting point range it is due to presence of impurity in the sample.

The presence of impurities decreases the melting point of any substance.

The sample is not pure. It has small impurities in it.

Explanation:

When the substance are pure, they have

In the above case, the known sample has M.P 134-137 centigrade, while recorded sample has M.P 125-126 degrees Celsius that's shows lowering of M.P is due to small amount of impurities.

Reason:

I.M.F become weak when impurities are present which consequently causes the lowering of M.P

i'm assuming that the correct answer is indeed the first one/ "a"..