Which of the following atoms has the larhest atomic radius na k mg ca

Out of the  following atom with largest atomic radius : Na ,K,Mg or Ca : K will have largest atomic radii

Explanation:

Atomic size

in is defined  as size of on atom or distance from nucleus to outermost shell of an atom.  

 ALONG GROUP -->  it increases.  

For example:- Consider 1st group

Li – 3  2,1    K,L  

Na- 11  2,8,1  K, L, M  

K- 19  2, 8, 8, 1  K,L, M, N  

As we move down the group. , every time a new shell is being added due to which size of an atom increases.  

Along  period - it decreases.  

For example:- consider 3rd period  

Na  Mg  Ar  Si  

2,8,12,8,22,8,32,8,4  

We see every time, a new electron is added to the same shell due to which nuclear charge increases and size decreases.  

That is the reason ,In the above asked question : out of all K is bigger .

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant.