Let a represent the red spheres and b represent the blue spheres. write a balanced equation for the equilibrium reaction.

I have attached the diagram related to this question.

5A₂ + 5B .................> 4A₂B + A₂ + B

Explanation:
1- For the reactants:
We can note that:
i- we have 5 moles of substance A which is diatomic. This means that we have 5A₂
ii- we have 5 moles of substance B which is monoatomic. This means that we have 5B
Based on the above, for the reactants side, we have:
5A₂ + 5B

2- For the products:
We can note that:
i- we have 4 moles of a substance formed from the combination of two moles of substance A with one mole of substance B. This means that we have 4A₂B
ii- we have one mole of substance A that is diatomic. This means that we have A₂
iii- we have one mole of substance B that is monoatomic. This means that we have B
Based on the above, for the products side, we have:
4A₂B + A₂ + B

3- Combining reactants and products parts:
Combining the reactants side (from part 1) with the products side (from part 2), we can find that the initial equation is as follows:
5A₂ + 5B .................> 4A₂B + A₂ + B

4- Balancing the equation:
Taking a look at the initial equation we reached in part 3, we will find that:
Number of moles of substance A in reactants = 2*5 = 10 moles
Number of moles of substance A in products = 2*4 + 2*! = 10 moles
SUBSTANCE A IS BALANCED
Number of moles of substance B in reactants = 5*1 = 5 moles
Number of moles of substance B in products = 4*1 + 1 = 5 moles
SUBSTANCE B IS BALANCED
Based on the above, the final balanced equation is the same as the initial equation reached in part 3:
5A₂ + 5B .................> 4A₂B + A₂ + B

Hope this helps :)

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. 

The problem here is that according to aufbau principle before 3d orbital 4s subshell comes.after filling 3p orbital with electrons you have 4 electrons left, you place two in 4s with opposite spin and the other two in 3d in any of its two orbitals of total five orbitals with the same spin.