7. Identify the substance if a 5g sample is found to have a volume of 2.5ml. Substance Density (g/mL)
A. 12.5
B. 2.0
C. 0.50
D. 10

B

Explanation:

Density ( as shown) = g/ml

   density =  5 g / 2.5 ml =  2 g/ml

carla slowed down in the beginning of her trip, stopped, and then sped up

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.