The gas tank of dave’s car has a capacity of 12 gallons. the tank was 38 full before dave filled it to capacity. it cost him $2.50 per gallon of gas. how much did dave spend, in dollars, to fill the tank to capacity?

$ 18.75            

Explanation:

given,                                              

capacity of the Dave’s car = 12 gallons

Assuming that the tank is 3/8 full before

Cost of gas per gallon =  $2.50 per gallon of gas

Volume Dave have to fill                      

       =                          

       = of full tank              

       =              

volume Dave have to fill = 7.5 gallons          

total money Dave spent                  

     = 7.5 gallons x $2.50                

     = $ 18.75                                            

Dave have to spend $ 18.75 to fill tank to it capacity.

the answer would be c

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.