Solution,
Mass of Mg - 21gm
molar mass of Mg - 24gm
moles = Given mass/ Molar mass
moles = 21/24 = 0.875
1 mole of Mg produce 1 mole of H2 gas
so 0.875 mole of Mg will produce 0.875 moles of H2 gas
One mole of H2 gas = 22.4 litre
0.875 mole of H2 gas = 0.875×22.4
0.875 mole of H2 gas = 19.60 litre
So the nearest ANSWER is Option four 19.37 litre.
Explanation:
Given parameters:
Dimension = 8.5in²
we are to convert from in² to cm²
in² = in x in
cm² = cm x cm
1 in = 2.54cm
Using dimensional analysis;
8.5in² x 
= 54.84cm²
We solved this problem using dimensional analysis where we multiplied the unit with 1.
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Answer:
B) sand
Explanation:
A) Oil is a wrong choice because it is a liquid not a solid and also if it is oil, it will float over the water surface as a droplets.
B) Sand is the right choice, because sand is a solid and it does not dissolve in water and stabilizes at the bottom.
C) Sugar is a wrong choice, because small amount of sugar will dissolve in water and be a homogeneous solution and does not appear as a particles.
D) Wood ships is also a wrong choice, even it is a solid and does not dissolve in water, but it will float over the water surface.