Answer
a) $2Cr + 3Cl_{2} → 2CrCl_{3}$
b) $SiO_{2} + 2C → Si + 2CO$
c) $3Fe + 4H_{2}O → Fe_{3}O_{4} + 4H_{2}$
Work Step by Step
a) $2Cr + 3Cl_{2} → 2CrCl_{3}$
two moles of chromium reacts with three moles of chlorine to form two moles of chromium chloride.
b) $SiO_{2} + 2C → Si + 2CO$
one mole of silica reacts with two moles of carbon to free the silicon and oxidize the carbon as carbon monoxide.
c) $3Fe + 4H_{2}O → Fe_{3}O_{4} + 4H_{2}$
three moles of iron in pure state oxidizes with four moles of water to form one mole of ferric oxide and four moles of hydrogen.
