For the reaction n2(g) + 3h2(g) 2nh3(g), what will happen if hydrogen gas was removed from the reaction mixture? there will be a shift toward the products. there will not be a shift in equilibrium. there will be a shift toward the reactants. the value for keq will change.

This uses something called Le Chatelier's principle. It states essentially that any stress put upon a system will be corrected.

In more simple terms, it means that in an equilibrium, such as the equation N2(g) + 3H2(g) <=> 2NH3(g), removing a reactant will cause the system to create more of said reactant to compensate for its loss, or adding excess reactant will cause the system to remove some of the added reactant. For future reference, the same principle applies to products in an equilibrium as well. 

In this case, hydrogen gas is a reactant, and hydrogen is being removed. According to Le Chatelier's principle, the system will shift to create more hydrogen gas. In essence, it will shift in the direction of the hydrogen gas, so there will be a shift toward the reactants.

To clear something up, Keq will not change, as it is a constant value with constant conditions (such as temperature, pressure, etc.).

I'm not sure but i will try to find out

The density of water is 1 g/cm cubed and in order for the pebble to sink its density has to be greater than the density of water and in order for the twig to float its density has to be less than the density of water