An ionic compound is composed of ionic bonds that are formed by transfer of electrons from one atom to the other. The atom that loses electrons acquires a positive charge (cation) while that which gains electrons acquires a negative charge.
In the case of sodium chloride; Sodium Na has 1 electron in its outer orbital while Chlorine Cl has 7 electrons. Thus, Cl requires 1 electron to complete its octet. This electron is donated by Na.
Thus, NaCl is essentially, Na⁺Cl⁻
Ans D) Chlorine becomes an anion by gaining an electron from sodium
Answer: A) The mass of the cup of frozen water is 12 grams which means the mass did not change
Explanation:
The mass of water did not change, because the amount of matter is the same: by the law of mass conservation you can assure that the mass of water (12 grams) is the same at the begining than the end.
Both in the physical changes (as in the case of the changes in the phases of the matter) and in the chemical changes, the law of conservation of the mass is obeyed. Therefore, assuming that the liquid water did not spill from the sealed container during the night, the mass remained constant (12 grams).
Regarding the fact that Josh noticed the cup had cracked on its sides, you must observe that water is an exception to the common behavior of the matter: most substances shrink when pass from liquid state to solid state due to the fact that the particles (atoms, molecules or ions) lose kinetic energy and they the approach each other occupying less space.
Being the density inversely relatated to the volume (density = mass / volume), this increase on volume means that the substances will increase its density when pass from liquid to solid.
But water is a remarkable exception. Water density reaches its maximum at about 4°C, which means that solid water (0°C) is less dense than liquid water.
Hence, ice (solid water) will ocuppy more space (more volume) than the same amount of liquid water, which is the reason why the liquid water in the plastic cup expanded when it froze, cracking the cup.
Sedimentary, igneous and metamorphic
Answer: A. 0.0375
Explanation:
To calculate the moles :

According to stoichiometry :
As 5 moles of
give = 2 moles of 
Thus 0.094 moles of
give =
of 
Thus 0.0375 moles of
will be produced when 3.00g of O₂ react completely
He discovered the atom while standing on a beach talking. Although, he thought the atom was like a ping pong ball.