Answer:
C is the only reasonable answer.. but this is 6th grade science and I'm in 7th, so I'm pretty sure I'm right
Ok, after doing an immense amount of research I came up with the most logical answer.
A. Is indicated by a negative enthrall sign.
Reasoning: an endothermic reaction is ice melting and the energy being more than its surroundings. Not specified to ice but as an example, ice is endothermic. That puts d and b out of the running leaving you left with a and c.
When I searched up enthalpy, it said “When a substance changes at constant pressure, enthalpy tells how much heat and work was added or removed from the substance.” Which is similar to c, right? Yeah, meaning both a and c are similar in that aspect.
The reason I decided to go with a is because heat is NOT released into the surrounding, exothermic reactions release energy and heat into the surrounding.
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.
<span>B. electron = negative; proton = positive; neutron = no charge </span>
