How many neutrons does an element have if its atomic number is 56 and its mass number is 152?

The value of keq for the equilibrium n2 (g) o2 (g) 2 no (g) is 4.2 x⋅10-31 at 27 °c. what is the value of keq for the equilibrium below

If a substance changes from one phase to another, is it still same substance? why

Electric fields can be seen by human eyes. O A. True O B. False

Cobalt-63 has a half-life of 5.3 years. If a pellet that has been in storage for 15.9 years contains 40.0g of Cobalt-63, how much of this radioisotope was present when the pellet was put into storage? Show work.

2. Where are valence electrons located?

Attempt 2 A sample of gas contains 49.16 % N 2 gas, 19.85 % Br 2 gas, 9.95 % CO 2 gas, and 21.04 % of an unknown gas. The average atomic mass of the gas mixture is 50.71 u. Calculate the atomic mass of the unknown gas.

A chemist determined by measurements that. 040 moles of gold participated in a chemical reaction. calculate the mass of gold that participated in the chemical reaction. round your answer to significant digits.

10) A screwdriver has the density of 5.5 grams per cubic centimeter. It also has the mass of 2.3 grams. What is the screwdriver's volume?

A chemist weighed out 20.7 g of sodium. Calculate the number of moles of sodium she weighed out

If 1.00 mol of argon is placed in a 0.500-L container at 20.0 ∘C, what is the difference between the ideal pressure (as predicted by the ideal gas law) and the real pressure (as predicted by the van der Waals equation) ? For argon, a=1.