Answer is: <span>(CH3)C.
Carbon has four bonds in organic compound.
1) in </span>(CH3)CH, carbon has four single bonds, one with hydrogen and three witn methyl group (CH₃), <span>so he is not radical.
2) in </span><span>(CH3)C, carbon has three single bonds and one free electron.
3) in </span>(CH3)C+, carbon has three single bonds and no free electrons, he is carbocation, not radical.
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.
Opinion : I disagree recycling can help them, but it still will not clear the environment.
Answer: pH = 3.15
Explanation: Solved in the attached picture.
