The best choice would be letter C hope this helps
The decimal point is placed after two digits starting from the end. For each decimal place, we can write the number divided by 100.
21.12 can be written as
.
Divide the numerator and denominator by 2:

The numerator and denominator can be divided by 2 again:

There is no other common factor between numerator and denominator other than 1. Hence, it is the reduced form.
Answer:infrared radiation
Explanation:
Most remote control uses infrared radiation
Answer:
For vector u, x component = 10.558 and y component =12.808
unit vector = 0.636 i+ 0.7716 j
For vector v, x component = 23.6316 and y component = -6.464
unit vector = 0.9645 i-0.2638 j
Explanation:
Let the vector u has magnitude 16.6
u makes an angle of 50.5° from x axis
So 
Vertical component 
So vector u will be u = 10.558 i+12.808 j
Unit vector 
Now in second case let vector v has a magnitude of 24.5
Making an angle with -15.3° from x axis
So horizontal component 
Vertical component 
So vector v will be 23.6316 i - 6.464 j
Unit vector of v 
First, we need to know the amounts of the elements in the compound.
Tin (Sn)= 5.28 g
Fluorine (F) = 8.65 - 5.28 = 3.37 g
Convert these to units of moles by dividing the molar masses.
Tin (Sn)= 5.28 g / 118.71 g/mol = 0.044 mol
Fluorine (F) = 3.37 g / 19.00 g/mol = 0.177 mol
Divide both by the least number of moles of the two.
Tin (Sn)= 0.044 mol / 0.044 mol = 1
Fluorine (F) = 0.177 mol / 0.044 mol = 4
Therefore, the empirical formula would be:
SnF4