19. A sample of an element has a volume of 78.0 mL and a density of 1.85 g/mL. What is the mass in grams of the sample? identify the information you are given. A. 42.2 g
B. 76.2 g
sC. 144 g

Explanation:

The mass of a substance when given the density and volume can be found by using the formula

From the question

volume = 78.0 mL

density = 1.85 g/mL

We have

mass = 78 × 1.85 = 144.3

We have the final answer as

Hope this helps you

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.