Three test tubes contain white crystalline organic solids a, b, and c, each of which melts at 149-150 degrees c. a 50-50 mixture of a and b melts at 130-139 degrees c. a 50-50 mixture of a and c melts at 149-150 degrees c. in what range would a 50-50 mixture of b and c probably melt? what can you say about the identities of a, b, and c?

The mixture of B and C will melt as 130 - 139 ºC.

Explanation:

If the melting point (130 - 139 ºC) of a mixture of A and B is lower than the pure substances that is 149 - 150 ºC that means that one of these susbtances is an impurity because reduces the melting point.

If the melting point of the mixture of A and C is the same as the pure substances, we can deduce that they are the same substances, also because the melting point when a substance is pure is just 1 or 2 ºC like in this case.

So in a Mixture of B and C is going to be like the first case of the mixture among A and B, because the B substance is the impurity.

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.

you need to have a picture of the atom that way we can answer it