Carbon is placed in ________ period and group _______ in the periodic table.

A period is determined by the number of shells and the group is determined by the number of electrons present in the outermost shell. Carbon has atomic number 6 and its electronic configuration is 2,4. It has two orbits and hence 4 electrons in the outermost shell, hence it is placed in the second period and group 4 in the periodic table.