Which of the following forms more than $\frac{1}{2}$ of a cell?

When a living tissue is ground in trichloroacetic acid to form a slurry and filtered through cheesecloth or cotton,the $.....$ passes through the cheesecloth or cotton.

Which four mineral elements constitute $99\%$ of the total mineral composition in a living system?

$A$: $CO_2$ is an organic compound.
$R$: $CO_2$ is a carbon compound.

Which of the following elements is present in negligible amounts in the human body?

Living cells contain $60-75\%$ water. How much water is present in the human body?