Why is a scale model of a system helpful to scientists? 1: Scales models while not an accurate measure for relative size, help to understand distance.

2: Scale models help to understand why moons fall into orbit around planets.

3: Scale models help to understand for relative sizes and distances of planets in actual system.

4: Scale models, while not accurate in measure for relative distance, help to understand size.

P. S: Please answer this as simple as possible.

Now consider the reaction when 45.0 g naoh have been added. what amount of naoh is this, and what amount of fecl3 can be consumed by it?

1)each group 16 element has how many valence electrons? ( )4 ( )6 ( )8 ( )16 2)how many dots appear in the dot structure for calcium ion, ca2+? ( )zero ( )one ( )two ( )eight 3) which of the following atoms forms a cation to obtain an octet of outer shell electrons? ( )magnesium ( )oxygen ( )fluorine ( )helium 4) an al3+ ion contains 13 protons and 10 electrons. ( )true ( )false 5) valence and non-valence electrons are represented in lewis dot structures. ( )true ( )false

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