Which kind of nuclear decay does not alter the identity of the atom?

gamma decay

Explanation:

1. Alpha decay: In this process, alpha particles is emitted when a heavier nuclei decays into lighter nuclei. The alpha particle released has a charge of +2 units.

2. Beta-decay: In this process, a neutron gets converted into a proton and an electron releasing a beta-particle. The beta particle released carries a charge of -1 units.

3. Gamma decay: in this process, an unstable nuclei gives off excess energy by a spontaneous electromagnetic process and releases . These radiations does not carry any charge and are electrically neutral and thus the identity of the atom undergoing gamma decay do not change.

At equilibrium state, the water will have turned into ice.

Explanation:

An Equilibrium phase is defined as a stage when chemical potential of any component ( solid liquid or gas) present in the system remains steady with time. So, in this situation, because the system is perfectly insulated, no heat will be gained or lost. The water and ice are both at exactly 0 °C, then that temperature will remain constant. As time goes on, the water will freeze and the system will become all ice.