I’m guessing it would be A because the river discharge tends to gather near coastlines where the river ends

This reaction is called decomposition reaction, furthermore it can be said to be decomposition of limestone.
The balanced chemical equation for the reaction is ~

Answer : The isoelectronic groups are:



Explanation :
Isoelectronic : It is defined as the compound or molecule having the same number of electrons and the same number of electronic structure.
- The element is helium. The number of electrons are 2.
- The element is beryllium. The number of electrons are 4. The number of electrons in
= 4 - 2 = 2 - The element is lithium. The number of electrons are 3. The number of electrons in
= 3 - 1 = 2 - The element is nitrogen. The number of electrons are 7. The number of electrons in
= 7 + 3 = 10 - The element is neon. The number of electrons are 10.
- The element is sulfur. The number of electrons are 16. The number of electrons in
= 16 + 2 = 18 - The element is magnesium. The number of electrons are 12. The number of electrons in
= 12 - 2 = 10 - The element is titanium. The number of electrons are 22. The number of electrons in
= 22 - 4 = 18 - The element is potassium. The number of electrons are 19. The number of electrons in
= 19 - 1 = 18
The isoelectronic groups are:



Answer:
Given: 42 g of N2
Solve for O2 mass that contains the same number of molecules to 42 g of N2.
Solve for the number of moles in 42 g of N2
1 mole of N2 = (14 * 2) g = 28 g so the number of moles in 42 g of N2 is equal to 42 g / 28 g per mole = 1.5 moles
Solve for mass of 1 mole of oxygen
1 mole of O2 = 16 g * 2 = 32 g per mole
Solve for the mass of 1.5 moles of oxygen
mass of 1.5 moles of O2 = 32 g per mole * 1.5 moles
mass of 1.5 moles of O2 = 48 g
So 48 g of O2 contains the same number of molecules as 42 g of N2
The mass of electrons, protons, and neutrons:
electrons 9.10938291*10^-31 kg
protons 1.67262178*10^-27 kg
neutrons 1.6749*10^-27 kg
the mass of electrons is way smaller than both, the mass of protons and neutrons
therefore, 1) the mass of 2 electrons is the smallest