In dna, guanine always forms hydrogen bonds with?

The DNA or deoxyribonucleic acid is composed of a pentose sugar, a base and phosphate group. The bases are adenine, thymine, cytosine and guanine. Guanine always forms hydrogen bonds with cytosine. Remember the statement “Apples in the Tree, Cars in the Garage”. The A stands for adenine and pairs with T-thymine then C – cytosine and G – guanine. 

"among the transition metal elements, manganese and zinc have a slight lowering of electronegativities. the reason behind this is that the nuclear charges of these elements are slightly weaker than the other transition metal elements due to the way their valence electrons are filled up. both manganese and zinc have their valence electrons filled up to the 4th shell with 1 pair of electrons (4s2) completely occupying it. although the electrons in the 3rd shell (3d) are yet to be paired since the outer most shell is filled up, the ability of the nucleus to attract electrons is lessened. hence,   the electronegativity (or the ability to attract electrons) is lessened."

shield volcanos are angry and get mad over the smallest things so much that there heads erupt   pahoehoe and a'a lava. a composite volcano is the poller opposite of a shield volcano. its   peaceful thing and knows how to control its emotions.