Question

1. which equation represents the law of conservation of matter?

a. h₂ + o₂ → h₂o
b. na + cl → nacl
c. 2na + o₂ → 2nao
d. fes + 2hcl → fecl + 2h₂s

Explanation:

Step1: Check atoms balance in option a

For \(H_2 + O_2
ightarrow H_2O\), hydrogen atoms: \(2\) (left) vs \(2\) (right). Oxygen atoms: \(2\) (left) vs \(1\) (right). Not balanced.

Step2: Check atoms balance in option b

For \(Na+Cl
ightarrow NaCl\), chlorine atoms: \(1\) (left) vs \(1\) (right). Sodium atoms: \(1\) (left) vs \(1\) (right). But chlorine exists as \(Cl_2\) in nature. Not correct formula.

Step3: Check atoms balance in option c

For \(2Na + O_2
ightarrow 2NaO\), sodium atoms: \(2\) (left) vs \(2\) (right). Oxygen atoms: \(2\) (left) vs \(2\) (right). But sodium oxide formula is \(Na_2O\). Incorrect formula.

Step4: Check atoms balance in option d

For \(FeS + 2HCl
ightarrow FeCl_2+ H_2S\), iron atoms: \(1\) (left) vs \(1\) (right). Sulfur atoms: \(1\) (left) vs \(1\) (right). Hydrogen atoms: \(2\) (left) vs \(2\) (right). Chlorine atoms: \(2\) (left) vs \(2\) (right). Balanced.

Answer:

d. \(FeS + 2HCl
ightarrow FeCl_2+ H_2S\)