heh.......... sorry man............... but this was posted over 5 hours ago........ so nobody is gonna see it and you probably dont need the answer anymore..... so errrr..... imma justtttt..... take these points :D
The mass change, or the mass defect, can be calculated by the formula that is very known to be associated with Albert Einstein.
E = Δmc²
where
E is the energy gained or released during the reaction
c is the speed of light equal to 3×10⁸ m/s
Δm is the mass change
(1.715×10³ kJ)(1,000 J/1 kJ) = Δm(3×10⁸ m/s)²
Δm = 1.91×10⁻¹¹ kg
Explanation:im not really sure about this one but i think it is either c or b
ANSWER:C im pretty sure.sorry if wrong
Answer:
I think the answer is the 3rd one
Mg(s)+2HCl(aq)→MgCl2(aq)+H2(g)
(since the molar mass of Mg is not given, assuming that it's mola mass is 24gmol¯1)
1st find the moles of Mg using the equation n=m/M where
n - moles
m - mass
M - molar mass
Therefore :

n = 0.39375mol
n = 0.39mol
Then using the equation n=V/Vm where;
n = mol
V = volume
Vm = molar volume
Find the volume.
n = V/Vm
(n =0.39mol , Vm = 22.4dm³mol¯¹)
V = 0.39mol×22.4dm³mol¯¹
V = 8.736dm³