Answer:
B. 18
Explanation:
An atom, which is the smallest indivisible particle of matter, further contains certain particles called SUB-ATOMIC PARTICLES namely: proton, neutron and electron. In a neutral/uncharged atom, the number of proton is equal to the number of electrons. The number of protons in an atom represent its ATOMIC NUMBER.
However, the sum of the proton number and neutron number gives the MASS NUMBER i.e. mass no. = proton no. + electron no.
Hence, according to this question which states that an atom has an atomic number of 17 and a mass number of 35. The neutron no. can be calculated as follows:
Neutron no. = mass no. - proton no.
Neutron no. = 35 - 17
Neutron no. = 18
