Breaking a glass
Crushing a can
Chopping wood
Boiling water
Mixing sand and water
Melting and ice cube
Let's see. It's definitely not the O horizon, because that layer is at the very top. A is already eliminated. Same thing with the A horizon, that is actually the top soil. C is out. It has to be either B or D. A D layer doesn't exist, so B is out. But the B horizon is considered a region of subsoil. The answer is D: B horizon.
Molar mass:
CaH2 = 42.094 g/mol
H2 = 2.01 g/mol
<span>CaH2 + 2 H2O = Ca(OH)2 + 2 H<span>2
</span></span>
42.094 g ------------------------------ 2 x 2.01 g
?? ( mass of CaH2) --------------- 4.550 g
4.550 x 42.094 / 2 x 2.01 =
191.5277 / 4.02 => 47.64 g of CaH2
hope this helps!