Please help solve the following questions

Which of the following statements is true? question 4 options: nuclear decay rates vary with the conditions of the reaction, but chemical reaction rates do not. chemical reaction rates vary with the conditions of the reaction, but nuclear decay rates do not. neither chemical reaction rates nor nuclear decay rates vary with the conditions of the reaction. both chemical reaction rates and nuclear decay rates vary with the conditions of the reaction.

When the earth was formed and cooled, why did nickel and iron end up in the center of the earth while basalt and granite ended up in the outer layers

Ahydrogen atom has 1 electron. how many bonds can hydrogen form? a) 1 b) 2 c) 3 d) 4 e) 5