Answer:
The correct answer is - D. Freezing point depression.
Explanation:
When rock salt is spread over snow-covered icy roads, it generates a liquid layer over it by melting from the surface thereby lowering or depression in the freezing point below the ice.
Therefore, due to this liquid layer comes into the contact with the ice present on the road and causes other ice to melts. This keeps on decreasing the volume of the ice on the road therefore, rock salts spread on the roads during a snowstorm.
Explanation:
A post-test or a mastery test can be unlocked if the learner who has the of it previously can complete the given tutorial with the test.
After the tutorial with the test, the learner will have to complete everything and if he passes the test with a completed answer then he will see that the Mastery Test has been unlocked. Also after the mastery test is unlocked it can be done again.
Answer: 1. The empirical formula is
2. The molecular formula is 
Explanation:
If percentage are given then we are taking total mass is 100 grams.
So, the mass of each element is equal to the percentage given.
Mass of P = 37.32 g
Mass of N = 16.88 g
Mass of F = 45.79 g
Step 1 : convert given masses into moles.
Moles of P =
Moles of N =
Moles of F =
Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.
For P = 
For N = 
For F =
The ratio of P: N: F= 1: 1: 2
Hence the empirical formula is 
The empirical weight of
= 1(31)+1(14)+2(19)= 82.98 g.
The molecular weight = 82.98 g/mole
Now we have to calculate the molecular formula.

The molecular formula will be=
The answer is sodium (Na)
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