Which of the following elements has the largest atomic radius? potassium calcium cobalt nickel someone

Ameter stick is pivoted at the 0.50-m line. a 3.0-kg object is hung from the 0.15-m line. where should a 5.0-kg object be hung to achieve equilibrium (the meter stick oriented horizontal and motionless)?

The slope of a velocity time graph over any interval of time gives the during that interval

Why should the wavelength scale of spectroscope be calibrated