The half-life period for a first order reaction is independent of 1) rate constant
2) Concentration
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2 concentrations

Explanation:

Gogle - " The half-life of a reaction is the time required for a reactant to reach one-half its initial concentration or pressure. For a first-order reaction, the half-life is independent of concentration and constant over time. "

these nuts

the positions which points up in upward carbon and down in downward carbon are axial

and vice versa holds true for equatorial positions

so the correct answer with labelled diagram will be