We are asked to convert from units of kilometer per second to units of miles per year. To do this, we need a conversion factor which would relate the different units involved. We either multiply or divide this certain value to the original measurement depending on what is asked. From literature, we will find that 1 mile is equal to 1609 meters and 1000 m is equal to 1 kilometer. Also, we will find that 3600 s is equal to 1 hr, 24 hr is equal to 1 day and 365 days is equal to 1 year. We do the conversion as follows:
3.8 km / s ( 1000 m / 1 km ) ( 1 mile / 1609 meters ) ( 3600 s / 1 hr ) ( 24 hr / 1 day ) ( 365 days / 1 year ) = 74479055.3 miles per year
A sorry if it’s wrong good luck
The one whose molar mass is smaller than sodium.
Fluorine is 19 g
Chlorine= 35.5 g
Bromine= 80 g
so in sodium fluoride, the percent of sodium is the largest.
Heat require to boil 15.6 g iron from 122 C0to 355 C0 whereas,

Where, m is mass of iron
s is specific heat of iron
d T is change in temperature in celcius

If
1 cal = 4.2 J
Then,

Thus 0.389 k cal of enrgy is required by a 15.6 g Fe to reach to 355 C^0