Which statement correctly compares the masses of subatomic particles in an atom such as carbon? A- an electron has a greater mass than a proton .
B- A proton has about the same mass as an electron .
C- A proton has about the same mass as a neutron .
D- neutrons protons and electrons have the same mass .

The subatomic particles have been electrons, protons, and neutrons. The mass of protons have been equal to the mass of neutrons. Thus option C is correct.

The atoms has been found to be consisted of the positively charged nucleus and the negatively charged electrons. The nucleus has been consisted of the neutrons and protons.

The number of electrons and protons has been equal in an atom. The neutrons number has been varied in the atom. The mass of the electron has been negligible in an atom, and thereby the mass of the atom has been dependent on the mass of the nucleus.

The mass of the neutrons has been almost equal to the mass of protons. Thus option C is correct.

For more information about subatomic particles, refer to the link:

link

C- A proton has about the same mass as a neutron .

Explanation:

In an atom such as a carbon atom, the masses of the proton and neutrons are the same.

The mass of the electrons is very negligible.

The mass of protons and neutrons are similar.

part 1: the half-life of the element is 22 years.

part 2: it will take 132.02 year for the sample to decay from 308.0 g to 4.8125 g.

explanation:

part 1: there are two ways to determine the half life time.

first way: the half life time can be determined directly from its definition as it is the time required for the sample to decay to its half concentration.

from the data the initial concentration was 45.0 g and decayed to its half value (22.5 g) in 22.0 years.

second way: the radio active decay is considered first order reaction so we can use the laws of first order reactions.

k = (1/t) ln (a/a-x), where k is the rate constant of the reaction,

t is the time of the reaction

a is the initial concentration of the reactant

a-x is the remaining concentration at time (t)

a = 45.0 g the initial concentration at t = 0 year.

at t = 22 year, a-x = 22.5 g

then k = (1/22 year) ln (45.0 g/ 22.5 g) = 0.0315 year-1.

the half-life time (t1/2) = ln 2/ k = 0.693/ k =0.693/ 0.0315 = 22 years.

part 2:

using the same law k = (1/t) ln (a/a-x),

using the given data; a = 308.0 g and a-x = 4.8125 g and the calculated k from the part 1 (k = 0.0315 year-1)

t = (1/k) ln (a/a-x) = (1/0.0315) ln (308.0/ 4.8125) = 132.02 years