Answer: Option (c) is the correct answer.
Explanation:
Wood is a mixture of different substances. Primarily it consists of cellulose, lignin, water etc.
When we heat wood then all these substance oxidize into the atmosphere even before they could melt.
Whereas iron, sodium chloride and ethanol all are the substances which can melt at any temperature.
Thus, we can conclude that out of the given options, wood, a mixture of different substances is a material that does not melt at any temperature.
Molarity is the number of moles of solute in 1 L of solution.
the mass of NaCl added - 20.45 g
number of moles of NaCl - 20.45 g / 58.5 g/mol = 0.350 mol
volume of the solution is 700.0 mL
since molarity is the number of moles in 1000 mL
and if 700.0 mL contains - 0.350 mol
therefore 1000 mL contains - 0.350 mol / 700.0 x 1000 = 0.500 mol
hence molarity of solution is 0.500 M
