Which of the following statements about ice melting is true?
a. energy flows from the ice to its surroundings.
b. water molecules move from their fixed position.
c. water molecules lose energy.
d. the temperature of the ice increases as it melts.

Two statements are true.

B. Water molecules move from their fixed position.

D. The temperature of the ice increases as it melts.

Explanation:

Ice is the solid state of water. The inter-molecular forces in ice is very strong.

But when we increase the temperature of ice then the inter-molecular force becomes weak and water molecules move from their fixed position and the inter-molecular force break then ice starts to melt.

When we the temperature increase of the ice then ice melts.

Hence, Two statements are true.

B. Water molecules move from their fixed position.

D. The temperature of the ice increases as it melts.

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.

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