If a block has a density of 1.8 g/ml, will it float?

NO, the block with density 1.8 g/ml will not float.

Explanation:

Density is the relationship between volume and mass, whereas buoyancy is the ability of an object to float. Its buoyancy influences the density of an object.  

For an object float its density should be less than the density of water.If the density is higher , then it will not be able to displace equal amount of water causing the object to sink.

Here the block with density 1.8g/ml would sink since its density is greater than the density of water. The density of water is 1g/cm cube,

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms

it's c (engineer's do their work with mechanical stuff not on any living being)