The question right above the data table : ))

is approximately the density of water under room temperature. The wood block will sink to the bottom of the cylinder if its density is greater than that of the water.

Steps for measuring volume of the wood block assumes that the wood block would float on top of the water. Otherwise there shall be no need for pushing the block underneath the water surface as in step b. The observation is now in conflict with the assumption. It is necessary to repeat the experiment. Consider revising the assumption and procedure if the discrepancy persists.

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.

i just learnt this recently but i need to look through my notes again