on a worksheet i have i found out the volume of the rectangle (34.2cm3) then it asks "If a block of H20 the mass would be..." i put 34.2g since that was the volume but not sure if im right?

To determine the mass of a block of water with a volume of 34.2 cm³, you need to consider the density of water. The density of water is approximately 1 g/cm³.

To find the mass of an object, you can use the formula:

Mass = Density × Volume

In this case, the volume is 34.2 cm³ and the density of water is 1 g/cm³.

By substituting these values into the formula, you can calculate the mass:

Mass = 1 g/cm³ × 34.2 cm³
Mass = 34.2 grams

So, your answer of 34.2 grams is correct. The mass of a block of water with a volume of 34.2 cm³ would indeed be 34.2 grams.