Fluorine gas is placed in contact with calcium metal at high temperatures to produce calcium fluoride powder. What is the formula equation for this reaction?
Upper F subscript 2 (l) plus upper N a (s) right arrow upper N a upper F subscript 2 (s).
Upper F subscript 2 (g) plus upper C a (s) right arrow upper C a upper F subscript 2 (l).
Upper F subscript 2 (g) plus upper N a (s) right arrow with delta above upper N a upper F subscript 2 (l)
Upper F subscript 2 (g) plus upper C a (s) right arrow with delta above upper C a upper F subscript 2 (s).

Upper F subscript 2 (g) plus upper C a (s) right arrow with delta above upper C a upper F subscript 2 (s).

Explanation:

This is a chemical reaction problem.

In expressing any chemical reaction, we need to understand that there are reactants and products.

Using the statement of this problem, we can deduce that;

 Reactants are Fluorine gas and Calcium metal

  Product is Calcium Fluoride

Note: A metal is a solid(s) and powder is a solid(s). A gas is denoted as (g). They depict the state of the species reacting.

                    F₂     +    Ca               →           CaF₂

We can see that equal number of atoms are on both sides of the expression.

in scientific notation, the value of the  speed of light in a vacuum

  will be written as 2.995 * 10^8. when this value is represented in the form of

  a * 10^b, then, a = 2.995 and b = 8.

the value of the speed of light in a vacuum given above can also be rounded up to approximately 300000000. in this case, the scientific notation will be written as 3 *10^8.