I believe it's C. 30
you have to find the pattern, so 15/3= 5
6x5= 30
Water takes longer to cool down and heat up because it detains temperature longer. So in the summer, coastal areas are cooler and the in the winter, coastal ares are warmer.
Molality is defined as the number of moles of solute in 1 kg of solvent.
molality of solution to be prepared is 0.50 molal
this means that in 1000 g of water there should be 0.50 mol of NaCl
if 1000 g of water should contain - 0.50 mol
then 750.0 g of water requires - 0.50 mol/kg x 0.750 kg = 0.375 mol
mass of NaCl in 0.375 mol - 58.5 g/mol x 0.375 mol = 21.9 g
therefore a mass of 21.9 g of NaCl is required
