ANSWER and EXPLANATION
We want to identify how to test to see if a sample is a metal or not.
To do this, the malleability of the sample can be tested. This is done by striking the sample with a hammer/mallet.
Metals are malleable i.e. they deform under pressure, compared to non-metals that crack under pressure.
Hence, if after striking it, it can be flattened or deformed then, it is metal but if it cracks or turns to powder, then it is not a metal.