Answer:
A- beryllium
B- calcium
C- magnesium
Explanation
NOTE: all element in group 2 have 2 balance electrons
First let’s start with B- number of electrons= number of protons which is equal to the atomic number. therefore, the answer is calcium as it’s atomic number is 20
C- magnesium will have three energy levels considering it has 12 electrons (2,8,2).
A- beryllium is the lightest one in group 2 as it has the atomic mass of 9.0122.
Answer:
Hydrogen.
Explanation:
We see in the nucleus that we have 1 proton and 1 neutron.
The number of protons in the nucleus determines which element it is.
Element with 1 proton is the 1st element on the Periodic Table, Hydrogen.
For this problem we assume that oxygen is an ideal gas. So, we use the equation PV=nRT where P is pressure, V is the volume, n is the number of moles, R is a universal constant and T is the temperature. We first solve for the number of moles n. Then, using the molar mass of oxygen we convert it to grams.
PV=nRT
n = PV / RT
n = 3.23 (8.5) / 0.08206 (32+273.15)
n = 1.0964 mol
mass = 1.0964 mol (32g / 1 mol) = 35.09 g O2
