What fraction of a 100 g sample of K - 42 will remain after 24.8 hours?

1/4

Explanation:

From the question given above, the following data were:

Original amount (N₀) = 100 g

Time (t) = 24.8 h

Fraction remaining =?

NOTE: The half-life of K–42 is 12.4 h

Next, we shall determine the number of half-lives that has elapse. This can be obtained as follow:

Time (t) = 24.8 h

Half-life (t½) = 12.4 h

Number of half-lives (n) =?

n = t / t½

n = 24.8 / 12.4

n = 2

Finally, we shall determine the fraction remaining. This can be obtained as follow:

Number of half-lives (n) = 2

Fraction remaining =?

Fraction remaining = 1/2ⁿ

Fraction remaining = 1/2²

Fraction remaining = 1/4

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.