A is your answer.
On the periodic table the atomic number is the number of protons inside the nucleus.
B , because some organelles located in plant cells are not present in the animal cell
D:
When electrons are gained, the charge of the atom decreases.
When you are given an atom with a charge, the oxidation of that atom is the charge. So by going from a Cr^3+ (Oxidation Number = 3) to a Cr^2+ (Oxidation Number = 2), the Oxidation Number thus decreases.
Answer: 
Explanation:
a) 
: This is a non polar covalent compound which are held by weak vanderwaal forces of attraction.
b) 
: This is a covalent compound which is polar due to the presence of lone pair of electrons and are held by dipole-dipole forces of attraction.
c) : These are joined by a special type of dipole dipole attraction called as hydrogen bond. It forms between electronegative nitrogen atom and hydrogen atom and is the strongest interaction.
d) 
: This is a covalent compound and is non polar which are held by weak vanderwaal forces of attraction.
e) 
: This is a covalent compound and is non polar which are held by weak vander waal forces of attraction.
