Which of the following has the smallest radius rb+, k, k+, or rb+

Option (c) is the correct answer.

Explanation:

It is known that when we move down a group then there is increase in size of atom. This is because there occurs increase in number of shells in the atom.

Also, when an atom loses electrons then it acquires a positive charge and size of the atom decreases. On the other hand, when an atom gain electrons then it acquires a negative charge and size of the atom increases.

Since, both Rb and K are same group elements and Rb has larger atomic size than K.

Hence, we can conclude that out of the given options has the smallest size.

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.

c) should be the answer.