Answer:
Group 18th
Explanation:
The group 18th of periodic table which is composed of Noble gases mainly was missing from the Mendeleev's periodic table. The reason for this is that Noble gases are least reactive, therefore, it was difficult to predict such elements which do not react with other elements.
Answer:
Lead atoms have 82 electrons and the shell structure is 2.8. 18.32. 18.4.
Explanation:
The ground state electron configuration of ground state gaseous neutral lead is [Xe].
Answer:
The answer to your question is the letter A. 1
Explanation:
Unbalanced chemical reaction
Mg + O₂ ⇒ MgO
Reactants Elements Products
1 Magnesium 1
2 Oxygen 1
Balanced chemical reaction
2Mg + O₂ ⇒ 2MgO
Reactants Elements Products
2 Magnesium 2
2 Oxygen 2
Conclusion
The coefficients of the balanced equation are 2, 1, 2
corrected question: A chemist adds 135mL of a 0.21M zinc nitrate solution to a reaction flask. Calculate the mass in grams of zinc nitrate the chemist has added to the flask. Round your answer to significant digits.
Answer:
5.37g
Explanation:
0.21M means ; 0.21mol/dm³
1dm³=1L , so we can say 0.21mol/L
if 0.21mol of Zinc nitrate is contained in 1L of water
x will be contained in 135mL of water
x= 0.21*135*10³/1
=0.02835moles
number of moles= mass/ molar mass
mass= number of moles *molar mas
molar mass of Zn(NO₃)₂=189.36 g/mol
mass= 0.02835 *189.36
mass=5.37g
