Question

draw the molecules. write the balanced equation at the bottom
$ce{sno_{2} + h_{2} -> sn + h_{2}o}$

Explanation:

Step1: Count atoms on each side

Reactants: Sn=1, O=2, H=2; Products: Sn=1, O=1, H=2

Step2: Balance oxygen atoms

Add coefficient 2 to $\text{H}_2\text{O}$:
$\text{SnO}_2 + \text{H}_2
ightarrow \text{Sn} + 2\text{H}_2\text{O}$
Now: Reactants: Sn=1, O=2, H=2; Products: Sn=1, O=2, H=4

Step3: Balance hydrogen atoms

Add coefficient 2 to $\text{H}_2$:
$\text{SnO}_2 + 2\text{H}_2
ightarrow \text{Sn} + 2\text{H}_2\text{O}$
Now: Reactants: Sn=1, O=2, H=4; Products: Sn=1, O=2, H=4

Step4: Verify all atoms balanced

All elements have equal counts on both sides.

Answer:

$\text{SnO}_2 + 2\text{H}_2
ightarrow \text{Sn} + 2\text{H}_2\text{O}$

(Note: For drawing molecules: $\text{SnO}_2$ is a solid network structure, $\text{H}_2$ is a diatomic molecule ($\text{H-H}$), $\text{Sn}$ is a metallic lattice, $\text{H}_2\text{O}$ is a bent molecule with two $\text{O-H}$ bonds)