Some alkenes have geometric (cis-trans) isomers because . all of the carbon atoms in the compound are rigid and cannot rotate the carbon atoms in the double bond are free to rotate the carbon atoms in the double bond cannot rotate each of the carbon atoms in the double bond has four different groups attached to it one of the carbon atoms in the double bond has two identical groups attached to it

in 1783 cavendish was working with his hydrogen gas and found that when he burned it and condensed the vapor it was water. this was very significant since it disproved the greek theory of elements completely since water was not a simple substance but the product of two gases. it was lavoisier who hearing of the experiment gave cavendish's gas the name hydrogen ("water-producer") and added that hydrogen burned by combining with oxygen and that water was a hydrogen-oxygen combination.

explanation:

the answer to your question is c

c-14 is carbon-14, or radiocarbon.   it is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.