Your answer is A....They have the same number of protons and neutrons, but a different number of electrons. They have the same number of protons and electrons, but a different number of neutrons. Different isotopes of an element have the same atomic number, but different mass numbers.....
The sun generates its energy by nuclear fusion of hydrogen nuclei into helium.
Answer:
atomic number of Be =4
electronic configuration :1s²2s²
but for Be2+ atomic number = 4-2 =2
electronic configuration : 1s²
Moles of CO₂ = mass / molecular weight
Moles of CO₂ = 4.4 / (12 + 16 x 2)
Moles of CO₂ = 0.1 mol
Each mole of gas occupies 22.4 L at STP. Therefore,
Moles of NH₃ = 5.6 / 22.4
Moles of NH₃ = 0.25 mol
Answer: D=8.27 g/cm³
Explanation:
Density is mass/volume. Mass is in grams and volume is in liters. In this case, the problem wants our volume to be in cm³. All we need to do is to make some conversions to convert kg/m³ to g/cm³.

With this equation, the m³ and kg cancel out, and we are left with g/cm³.
D=8.27 g/cm³