Describe what half-life is.
answer in a paragraph .

Half-life is defined as the quantity to reduce to half of its initial value.

Explanation:

The term half-life is generally used in nuclear physics which describes how long a stable atom can survive a radioactive decay or how quickly an unstable stable atom can undergo radioactive decay. Half-life is a constant and does not have any units.

The formula to calculate half-life:

N(t) =

Here N(t) is the quantity which is “not decayed”.

is the “initial quantity” of the substance.

λ is the “decay constant”

the formula mass of a molecule or a compound is the sum of the atomic weights of the atoms in its empirical formula

(that's what i know about formula mass)

hey there!

mass = 6.75 g

volume =   9 cm³

therefore:

d = mass / volume

d   = 6.75 / 9

d = 0.7 g/cm³

answer b