200 grams is the required mass of calcium chloride.
Molarity (M) is define as the no. of moles (n) of solute present in per liter of solution (V) i.e. M = n/V.
Given molarity of CaCl₂ = 0.720 M
Total volume of solution = 10×250 = 2500 mL = 2.5 L
Moles of CaCl₂ = 0.720×2.5 = 1.8 moles
Now we calculate the moles by using the below formula:
n = W/M, where
W = required mass = to find?
M = molar mass of CaCl₂ = 110.98 g/mol
Mass of CaCl₂ = 1.8 × 110.98 = 199.8 = 200g
Hence, option (3) is correct i.e. 200g. is the required mass of CaCl₂.
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