Questions

Permanent hardness of water may be removed by the addition of Sodium Carbonate.

Expendable properties are those properties that are consume in use or that lose their identity in use. It also include those properties that become an integral part of other property when put to use and those properties which have an expected service life of less than one year.

For neutral atoms, the periodic trends in atomic size can be described like this

Atomic size decreases when going from left to right across a period,
Atomic size increases when going from top to bottom down a group.

Let's use these trends to try and figure out which atom would have the largest radius.

If you look at elements that are located in the same group, potassium will have a larger atomic radius when compared with sodium. Likewise, bromine will have a larger atomic radius when compared with chlorine.

Now focus on potassium and bromine. Since potassium is located at the start of period 3, and bromine at the end of the same period, potassium will have a larger atomic radius than bromine, and thus the largest atomic radius of the four given atoms.

Footsteps. 

Yes, as you walk forward, you will leave the footstep behind you.

The Wind is what has no voice but cries, no wings but flutters, toothless but bites, mouthless but mutters.