In your lab group you combined salt and water. Then you compared what happens when an egg is placed in tap water versus salt water. You observed that the egg floated in the salt water, but sank on the fresh water. You and your lab partner discuss the cause of this difference and wonder if the combining of the salt and water caused a physical or chemical change. Choose ALL of the evidence that supports that a physical change has occurred. A) gas was produced

B) the density changed

C) the salt dissolved in the water

D) the salt and the water cannot be separated into their individual molecules

E) the salt and the water can still be separated into their individual molecules

the density changed, the salt dissolved in the water, the salt and the water can still be separated into their individual molecules.

Explanation: physical changes are changes in size, shape, or state. Another way to think about a physical change is any change not involving a change in the substance’s chemical identity. You cannot write a chemical equation for salt water because the chemical identity is still salt AND water

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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.