They tell you to have caution.
Covalent compounds are composed of atoms that are linked via covalent bonds i.e. bonds formed by mutual sharing of electrons. This is in complete contrast to ionic compounds which are held together by ionic bonds, i.e. bonds formed by complete transfer of electrons from one atom to the other.
In the given examples we have:
Barium nitrate: Ba(NO3)2 - Ionic
Dinitrogen tetroxide: N2O4- Covalent
Boron trifluoride: BF3-Covalent
Ammonium sulfate: (NH4)2SO4- Ionic
Carbon tetrachloride: CCl4- Covalent
Barium chloride: BaCl2 - Ionic
The products. Without a balanced chemical equation, there is no reaction that can take place. The products is the final reation and the reactants help the final reaction take place.
The answer to this question would be: isotonic
An isotonic solution has a same tonicity/concentration to the cell. This kind of solution will not cause osmosis to occur so it wouldn't shrink or swell the cells. This is why an isotonic solution is safer for the cells. The normal saline solution is isotonic to human cells and used frequently in medicine to replace body fluid.
I remember coming across this question and the options were:
KOH, HCN, NH₃, HI, Sr(OH)₂
Now, a substance with a low pH is one that dissociates completely in water to release hydrogen ions, while basic substances dissociate completely to release hydroxide ions. Therefore, in the order of increasing pH:
HI, HCN, NH₃, Sr(OH)₂, KOH