A sample of an unknown gas effuses in 12.1 min. an equal volume of h2 in the same apparatus under the same conditions effuses in 2.42 min. what is the molar mass of the unknown gas?

What are the five properties of hydrogen?

Which of the following is an example of a pure substance? A. air B. salt water C. granite D. aluminum

When making a molar liquid solution from a dry chemical stock, you must know the molecular weight of the compound. (A) True (B) False

Hannah just finished building a house of cards that stands four stories high. She is worried that it will fall down. Which of the following statements must be true? A. A house of cards is too fragile and must fall down eventually due to gravity. B.

What is the flaw in Rutherford's model?

What is the rough er connected to

Two students design an experiment to see if pushing or pulling a box across the floor is more effective. The first student pushes the box across the floor a distance of 20 feet and the second student times how long it takes.

15.00 g of NH4HS (s) is introduced into a 500. mL flask at 25 °C, the flask is sealed, and the system is allowed to reach equilibrium. What is the partial pressure of ammonia in this flask if Kp = 0.108 at 25 °C for: NH4HS (s) ⇄ NH3 (g) + H2S (g) ?

Among elements 1-18, which element or elements have the smallest effective nuclear charge if we use the equation zeff=z-s to calculate zeff? check all that apply.

Two clear solutions are placed in separate beakers. The first solution has a pH of 4, and the pH of the second solution is unknown. If the two solutions are mixed and the resulting pH is 5, the second solution must have