A compound X has a molecular ion peak in its mass spectrum at m/z 136. What information does this tell us about X

How are isotopes of the same chemical element alike? how are they different?

Lab reagent, hypothesis test. a reference solution used as a lab reagent is purported to have a concentration of 5 mg/dl. six samples are taken from this solution and the following concentrations are recorded: (5.32, 4.88, 5.10, 4.73, 5.15, 4.75) mg/dl. these six measurements are assumed to be an srs of all possible measurements from solution. they are also assumed to have a standard deviation of 0.2, a normal distributin, and a mean concentration equal to the true concentration of the solution. carry out a significance test to determine whether these six measurements provide reliable evidence that the true concentration of the solution is actually not 5 mg/dl.

The rate constant for the reaction below is 6.2 x 10−5 mol l−1 s −1. if the initial concentration of a is 0.0500 m, what is its concentration after 115 s?