Carbon and silicon are found in the earth's crust and in what type of bonds?

What would the difference of spectral lines emitted by hydrogen gas in distant galaxies which is normally found at a wavelength of 21 cm on earth, be observed at 21.1 centimeters?

An object starts from rest at point f and speeds up continuously as it moves around an oval. a. choose a point about 1/8 th of the way around the oval from point f, and label it point g. draw a vector to represent the velocity of the object at point g. b. determine the change in velocity vector   between points f and g.

Crowbar of 5 metre is used to lift an object of 800 metre if the effort arm is 200cm calculate the force applied