71.

A p-type material is electrically

• positive

• negative

• neutral

• depends on the concentration of p impurities

Li nucleus has three protons and four neutrons. Mass of lithium nucleus is 7.016005 amu. Mass of proton is 1.007277 amu and mass of neutron is 1.008665 amu. Mass defect for lithium nucleus in amu is

• 0.04048 amu

• 0.04050 amu

• 0.04052 amu

• 0.04055 amu