All of the covalent carbon-carbon bonds in unsaturated hydrocarbons share 2 pairs of electrons.
true
false

False. carbon-carbon bonds that share 2 pairs of electrons are double bonds. An unsaturated hydrocarbon isnt necessary to only have double bonds. they can also have single bonds or triple bonds.

The given statement is false.

Explanation:

An unsaturated hydrocarbon is a chain of carbon and hydrogen atoms in which adjacent carbon atoms are attached together through double or triple bond.

Since it is known that carbon atom forms covalent compounds so, an unsaturated hydrocarbon not only contains double or triple bonds it also has single bonds in between.

Thus, we can conclude that the statement all of the covalent carbon-carbon bonds in unsaturated hydrocarbons share 2 pairs of electrons, is false.

- 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