In which of these compounds are there twice as many oxygen atoms as hydrogen atoms

Answer:
[tex] H_2SO_4 [/tex]
Explanation:
In the first option, the compound [tex] HClO_3 [/tex] has 1 hydrogen atom and 3 Oxygen atoms. There are 3 times as many oxygen atoms as hydrogen atoms.
In the second option, the compound [tex] H_2SO_4 [/tex] has 2 hydrogen atom and 4 Oxygen atoms. That is 2:4 = 1:2. Therefore, there are twice as many oxygen atoms as hydrogen atoms.
In the third option, the compound [tex] H_2O [/tex] has 2 hydrogen atoms and 1 Oxygen atom. There are ½ times as many oxygen atoms as hydrogen atoms.
In the fourth option, the compound [tex] H_3PO_4 [/tex] has 3 hydrogen atoms and 4 Oxygen atoms. 4 oxygen atoms to 3 hydrogen atoms.