Answer:
a. BH₃
Explanation:
According to the octet rules, atoms reach stability when are surrounded by eight electrons in their valence shell when they combine to form a chemical compound.
From the options, the only compound in which the central atom does not meet the octet rules is BH₃. The central atom is boron (B), which has 3 electrons in its valence shell. When B is combined with hydrogen (H), 3 electrons from the 3 atoms of H are added. The total amount of electrons is 6, fewer than 8 electrons needed to meet the rule.
hope this helps
C, because a homogeneous mixture is evenly mixed.
All those others would be heterogeneous (not evenly mixed).
B I think is right. Hope this helps!
Answer:
That would be helium, with a melting point of 0.95 K (-272.20 °C)—although this happens only under considerable pressure (~25 atmospheres). At ordinary pressure, helium would remain liquid even if it could be chilled to absolute zero.
True, Robert Hooke was the first person to discover cells inside a cork.
