What is a tough, rigid, outer covering that protects some cells and gives them shape?

Using the first volume and temperature reading on the table as v1 and t1, solve for the unknown values in the table below. remember to use the rules of significant figures when entering your numeric response.

Asample of tin (ii) chloride has a mass of 0.49 g. after heating, it has a mass of 0.41 g.  what is the percent by mass of water in the hydrate?   %

What is the energy in joules of a mole of photons associated with visible light of wavelength 486 nm?