The statement is true. The octet rule refers to the general rule of thumb wherein atoms of main-group elements tend to bond with other atoms in such a way that each atom possesses eight electrons (octet) in their valence shell. They tend to form the same electronic configuration as the noble gases. However, there are some exceptions to this rule. One of which is silane, SiH₄. A hydrogen atom only has 1 valence electron and needs another electron to complete its energy level. This is unlike other atoms, for example, carbon which has 4 valence electrons and needs to form 4 covalent bonds to fill its energy levels. Thus, 4 hydrogen atoms need only 4 more electrons. This is given by the silicon atom which has 4 valence electrons. Therefore, when a silicon atom is bonded to 4 hydrogen atoms, the resulting molecule, SiH₄, is a stable one.
Density can be calculated using the following rule:
density=mass/volume
therefore,
volume=mass/density
we have mass=0.451g and density=0.824g/ml
substituting in the above equation, we can calculate the volume as follows:
volume = 0.451/0.824 = 0.547 ml
<h2>Frequency</h2>
Explanation:
Wave frequency is the number of waves that pass a fixed point in a given amount of time.
Wave speed is the speed at which a wave travels.
Let the wave speed be 
Let the wave frequency be 
Let the wave length be 
The wave speed,frequency and wave length are related by the equation 
.
When increases, increases on the other side to maintain equality when no other property is changing.
Molecules in a gas will have more movement than molecules in a solid. This is because the molecules in solid matter are packed very tightly together to maintain its shape, whereas with gases they are spaced much further apart and fairly free to move. Hope this helps!
