Copper would be the last to melt because it has the highest melting point!
Answer:
c.boron-11
Explanation:
The atomic mass of boron is 10.81 u.
And 10.81 u is a lot closer to 11u than it is to 10u, so there must be more of boron-11.
To convince you fully, we can also do a simple calculation to find the exact proportion of boron-11 using the following formula:
(10u)(x)+(11u)(1−x)100%=10.81u
Where u is the unit for atomic mass and x is the proportion of boron-10 out of the total boron abundance which is 100%.
Solving for x we get:
11u−ux=10.81u
0.19u=ux
x=0.19
1−x=0.81
And thus the abundance of boron-11 is roughly 81%.
Answer:
1.25mole of Mg(OH)₂
Explanation:
The reaction is between Mg(OH)₂ and HCl, this is a neutralization reaction between an acid and a base.
Mg(OH)₂ + 2HCl → MgCl₂ + 2H₂O
The balanced reaction equation is given above.
2 mole of HCl reacts with 1 mole of Mg(OH)₂
So, 2.5mole of HCl will react with 
= 1.25mole of Mg(OH)₂
The number of moles of Mg(OH)₂ is given as 1.25mol
Given 3.72 g of P and 21.28g of Cl, converting these to moles: ( 3.72 g P)(mol P/30.97 g P) = 0.12 mol P (21.28 g Cl)(mol Cl/35.45 g Cl) = 0.60 mol Cl P:Cl = 0.12/0.60, therefore P: Cl =1/5 Therefore, PCl5 hope it helps
