Will ${}{35}Cl$ and
${}{37}Cl$ have different valencies? Justify your answer.
No, ${}{35}Cl$ and
${}{37}Cl$ are the isotopes. So, they have same number of protons and electrons. Hence, their electronic configuration and valencies are also the same.
${}{17}^{35}Cl$ =
${}{17}^{37}Cl$ = 2, 8,7(K,L,M)
Valency of ${}{35}Cl$ and
${}{37}Cl$ = 8 - 7 = 1