Find the total mass of neutrons in 7 mg of  14C.The answer is: =4.0347×10−xkg. The value of x is

Mass of one neutron =1.675×10−27kg ∴ Mass of 24.088×1020 neutrons (in 7mg614C )  =1.675×10−27×24.088×1020 =4.0347×10−6kg