CHEM EXPERT NEEDED***

A volume of 150.0 mL of H2O is initially at 24.00 °C. A chilled steel rod at 2.50 °C is placed in the water and the final temperature of the system is 21.20 °C.

Specific heat of water = 4.184 J/(g⋅∘C) and the specific heat of steel = 0.452 J/(g⋅∘C)

Write the equation and calculate the mass of the rod.

The number to the right of an element's symbol (ex. c-12) identifies the of an isotope.

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.

Consider hydrogen in an excited state n = 5n=5 that emits photons to reach the ground state. there are various possible transitions other than straight to the ground state that can occur; for example, it can drop to the n = 3n=3 state followed by the n = 3n=3 to the ground state transition. which of the possible transitions will result in the emission of a photon in the visible region?