Asample of crystalline compound when heated in an open test tube, produced several droplets of water on the upper region of the tube. the residue dissolved in water forming a yellow brown solution. why should you conclude that the compound is not a true hydrate

Answer is: If the compound were a true hydrate it would form aqueous solutions of identical color both before and after heating.

For example, copper(II) sulfate pentahydrate (CuSO₄·5H₂O) form aqueous solutions of bright blue both before and after heating.

Hydrate is a substance that contains water or its constituent elements.

The difference in color shows that there has been a chemical change on heating so the water formed could be produced in that chemical change. Alternatively the material could still be a true hydrate and the anhydrous material may have undergone a change on heating so you can't really conclude anything.

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates

answer:

technetium is the most reactive. this is followed by silver. the least reactive out of these three elements is strontium.