An atom has a charge of -3 in its orbitals which statement must be true in order for this atom to have no net charge

The atom must lose its three extra electrons to make the atom over all neutral.

Explanation:

The three subatomic particles construct an atom electron, proton and neutron. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other. For example if neutral atom has 6 protons than it must have 6 electrons.

If an atom have -3 charge it means three more electrons are added. In order to make the atom overall neutral three more electrons must be removed so that negative and positive charge becomes equal and cancel the effect of each other and make the atom neutral.

Electron:

The electron is subatomic particle that revolve around outside the nucleus and has negligible mass. It has a negative charge.

Symbol= e⁻

Mass= 9.10938356×10⁻³¹ Kg

It was discovered by j. j. Thomson in 1897 during the study of cathode ray properties.

Proton and neutron:

While neutron and proton are present inside the nucleus. Proton has positive charge while neutron is electrically neutral. Proton is discovered by Rutherford while neutron is discovered by James Chadwick in 1932.

Symbol of proton= P⁺

Symbol of neutron= n⁰

Mass of proton=1.672623×10⁻²⁷ Kg

Mass of neutron=1.674929×10⁻²⁷ Kg

7.2

Explanation:

you first have to find the number of moles of nitrogen dioxide by using the number of moles for calcium nitrate and the mole to mole ratios

number of moles of calcium nitrate=mass/mm

=16.4/102

=0.16g/mol

then you use the mole to mole ratios

2 : 4

0.16: x

2x/2=0.64/2

x=0.32g/moles of nitrogen dioxide

then you use the formula for the volume

v=22.4n

=22.4×0.32

=7.2

I hope this helps