Which of the following groups of elements are in the main group? A. Nonmetals
B. Transition elements
C. Alkali metals

D. Halogens

Describe uniform velocity and variable velocity in short

Electromagnetic induction. a coil of wire contains n turns and has an electrical resistance r. the radius of each turn is a. initially, inside the coil there exists a uniform magnetic field of magnitude b0 parallel to the axis of the coil. the magnetic field is then reduced slowly. the current induced in the coil is i. how long does it take for the magnitude of the uniform field to drop to zero?

Awave has a wavelength of 7 mm and a frequency of 19 hertz. what is its speed?