Draw the Lewis structure of NF3

When will le chatelier's principle come into effect? at the beginning of a reaction, when there are only reactants when a reaction has reached chemical equilibrium when a catalyst is added to a reaction mixture when a reaction is occurring but not yet at equilibrium

If 1.63 times 10 negative 4 of helium dissolves in 100.0g of water, what is the concentration in parts per million

This drawing shows a human body system. what is the primary function of this body system?