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
Answer:
Thermal Energy
Explanation:
I'll give you an example, Rub your hands together. Then touch your face or leg to feel any temperature change. Most likely your hands are warmer.
Answer:
Polar covalent bond.
Explanation:
When the bond is formed between the atoms by sharing the electrons the bond thus have covalent character. The atom with larger electronegativity attract the electron pair more towards it self and becomes partial negative while the other atom becomes partial positive. When the electronegativity difference is less than 0.4 the bond is non polar covalent.
When bonded atoms have greater electronegativity difference i.e 2 or greater than two the bond is ionic because electron is transfer from low electronegative atom to highest electronegative atom.
For example:
In water the electronegativity of oxygen is 3.44 and hydrogen is 2.2. That's why electron pair attracted more towards oxygen, thus oxygen becomes partial negative and hydrogen becomes partial positive.
In case of H₂, Cl₂, Br₂ the bond has very high covalent character because of zero electronegativity difference.
Answer:-
Alpha decay
Explanation:-
Uranium 238 has atomic number 92 and mass number 238.
Thorium 234 has atomic number 90 and mass number 234.
So, the change in atomic number as uranium 238 disintegrates into thorium234 = 92 – 90 = 2
So, the change in mass number as uranium 238 disintegrates into thorium234= 238 – 234 = 4
We know that when an alpha particle is emitted, the mass number decreases by 4 and the atomic number decreases by 2.
So when an atom of uranium 238 undergoes radioactive decay to form an atom of thorium-234, alpha decay has occurred.
