Question

directions: select the equations that correctly demonstrate the law of conservation of matter.

• $h_2 + o_2 \

ightarrow h_2o$

• $2h_2 + o_2 \

ightarrow 2h_2o$

• $ch_4 + o_2 \

ightarrow co_2 + h_2o$

• $c + o_2 \

ightarrow co_2$

• $na + cl_2 \

ightarrow nacl$

Explanation:

Step1: Check $H_2 + O_2 \to H_2O$

Left: H=2, O=2; Right: H=2, O=1. Unbalanced.

Step2: Check $2H_2 + O_2 \to 2H_2O$

Left: H=4, O=2; Right: H=4, O=2. Balanced.

Step3: Check $CH_4 + O_2 \to CO_2 + H_2O$

Left: C=1, H=4, O=2; Right: C=1, H=2, O=3. Unbalanced.

Step4: Check $C + O_2 \to CO_2$

Left: C=1, O=2; Right: C=1, O=2. Balanced.

Step5: Check $Na + Cl_2 \to NaCl$

Left: Na=1, Cl=2; Right: Na=1, Cl=1. Unbalanced.

Answer:

$2H_2 + O_2 \to 2H_2O$
$C + O_2 \to CO_2$