A. 2
trust me i used to so this in middle school
Hhhhhhhhchchhchchchchchchchchchchchchchchc
Answer : The correct option is, 
Explanation :
Amino acid : The acid that contains two functional groups that are carboxylic group,
and ammine group,
.
When the two or more that two amino acids join together with the help of peptide bond, they produces polypeptide chain or protein.
The bond present between the two amino acid is called a peptide bond.
The peptide bond is a chemical bond that is formed between the two molecules when the nitrogen of one amino acid react with the carbon of another amino acid by releasing a water molecule. This is a dehydration synthesis or condensation reaction.
From this we conclude that, only two functional groups carboxylic group,
and ammine group,
are present in all amino acids.
Hence, the correct option is, 
Answer:
Ionic compounds are compounds whereas metals are elements. Ionic compounds are electrolytes whereas metals are conductors. Ionic compounds are brittle whereas metals are malleable and ductile. ... Most ionic compounds will dissolve in polar solvents like water whereas metals will either be insoluble or react with water.