One
molar mass NaCl
Na = 23
Cl =35.5
Molar mass = 58.6
mols = 450 / 58.5
mols = 7.69 mols
Concentration = mols / L
mols = 7.69
Volume = 4.5 kg = 4.5 L [1 liter weighs 1 kg]
C = 7.69 mol / 4.5 L
C = 1.71 mol/L
The question is unclear. I'm taking this to mean that you don't change the number of moles; you merely add 0.5 L to the volume.
Answer C = 7.69 / 5L = 1.54 mol / L
Two
I'm going to leave this. The wording just is not clear.
Three
More than you could grow in the entire planet earth for many centuries.
Ratio of sugar = 10 / (40 + 10 + 500) = 10 / 550 = 1:55 or 0.0182 to 1
Four
Guava Juice = (36 / 100 ) * 100% = 36%
Water = (64/100 ) * 100 = 64%
Volume = l x w x h
volume = 7 x 8 x 14
volume = 784...... C
False because when warm air rises cool air will often move in
