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	The chemical formula for water is H2O 		\\ \\


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	The chemical formula for water is $H_{2}O$		 \\ \\


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	The chemical formula for water is $\text{H}_{2}\text{O}$	 \\ \\


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	The chemical formula for water is H\textsubscript{2}O 		\\ \\


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	\newcommand{\tsbt}{\textsubscript}
		
	The chemical formula for water is H\tsbt{2}O	


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