Which among the following is/are correct about solution (true solution)? I. Concentration of solute will always be the same throughout a mixture
in a solution.
II. Solutions do not show scattering of light.
(a) only I (b) only II
(c) both I and II (d) none

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.  

the answer is c

tell me if wrong

4d^55s^1 ( third choice)