Answer: 770 g water are needed to dissolve 27.8 g of ammonium nitrate 
in order to prepare a 0.452 m solution
Explanation:
Molality : It is defined as the number of moles of solute present per kg of solvent
Formula used :
where,
n= moles of solute
Moles of 
= weight of the solvent in g = ?
Thus 770 g water are needed to dissolve 27.8 g of ammonium nitrate in order to prepare a 0.452 m solution
Answer:
7.46 g
Explanation:
From the balanced equation, 2 moles of Mg is required for 2 moles of MgO.
The mole ratio is 1:1
mole = mass/molar mass
mole of 4.50 g Mg = 4.50/24.3 = 0.185 mole
0.185 mole Mg will tiled 0.185 MgO
Hence, theoretical yield of MgO in g
mass = mole x molar mass
0.185 x 40.3 = 7.46 g
Answer : The 
must be administered.
Solution :
As we are given that a vial containing radioactive selenium-75 has an activity of 
.
As, 3.0 mCi radioactive selenium-75 present in 1 ml
So, 2.6 mCi radioactive selenium-75 present in 
Conversion :
Therefore, the must be administered.
Example of an element that has an electron distribution ending in s2p1 is Na or sodium. The complete electron configuration of Na 1s22s22p63s<span>1. </span>Example of an element that has an electron distribution ending in s2d2 is Ca or calcium. The complete electron configuration of Ca is 1s22s22p63s23p64s2.
