Which element has an ion that is smaller than an ion of calcium?

Achild has maximum walking speed of 1.6 m/s. what is the length of the child's legs? 0.26 m

50.)the diagram below represents the wave fronts produced by a point source moving to the right in a uniformmedium. observers are located at points a and b.compared to the wave frequency and wavelength observed at point a, the wave observed at point b has a(1) higher frequency and a shorter wavelength(2) higher frequency and a longer wavelength(3) lower frequency and a shorter wavelength(4) lower frequency and a longer wavelength

Is the ability of one substance to dissolve in another.