He could be blindfolded and know which was his and which was his sister's. All he would need to do is pick them both up and if they were too big then pick them up one at a time. The lumber might make it harder to tell, but this is a question about physical properties.
So there is a change in mass which for the purpose of this question should be quite different. His sister's ought to be much lighter than his. He would find it easier to pick up.
Electron because it’s more valid than neutron
When you heat up most substances it gives them more Kinetic energy and the substance becomes less arranged in an ordered state, further apart and move faster. therefore the answer is the first: They gain a higher average kinetic energy
Hope that helps :)
The answer is C ionic bonds
