Answer Csl POa 5) Calculate the number of atoms present in 2.25 g of helium? Ans
ID: 636293 • Letter: A
Question
Answer Csl POa 5) Calculate the number of atoms present in 2.25 g of helium? Answer: 6) How many milliliters of water must be added to 2.05 liters of a 4.44 molar solution of NaOH to make the resulting solution 3.88 molar? Answer 7) How many electrons are present in the N-3 ion? Answer: Telertrons 8) How many moles of iron are contained in 5.22 X 1022 atoms of iron Answer MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 9) What is the mass number of an atom of gold that has 200 neutrons? A) 241 B 279 C) 252 D) 222 E) 297Explanation / Answer
5. no of moles = W/G.A.Wt
= 2.25/4 = 0.5625moles
number of atoms = no of moles * 6.023*10^23
= 0.5625*6.023*10^23 = 3.38*10^23 He atoms
6. initial Final
M1 = 4.44M M2 = 3.88M
V1 = 2.05L V2 =
M1V1 = M2V2
V2 = M1V1/M2
= 4.44*2.05/3.88 = 2.35L = 2350ml
7. N^3- = 7+3 = 10 electrons
8. 6.023*10^23atoms = 1 mole of Fe
5.22*10^22 atoms = 1mole*5.22*10^22/6.023*10^23 = 0.0866 moles of Fe