i think it it covalent
Covalent compound
K is an element. It is elemental Potassium metal.
I'm not sure what you mean by "purely covalent", since the ionic-vs-covalent distinction is expressed in terms of electronegativity, which can take a range of values (higher values = more ionic). CO is very much a covalent compound though.
Gasoline is not a pure sybstance but is a mixture of covalent compounds mainly alkanes .
Hydrogen oxide (a.k.a. water) is a polar covalent compound.
Toothpaste is not a pure substance but is mixture of many ingredients some contain covalent bonds some ionic.
Covalent bonds are between non-metals only. Methane is a hydrocarbon (CH4. Therefore it is COVALENTLY bonded because of the bonds between carbon (non-metal) and hydrogen (non-metal). Ionic compounds only apply to those made of metals and non-metals.
Milk is a complex mixture of substances, so the question is meaningless. It can only be answered for a pure compound. Water makes up most of milk, and that is covalent, as are most of the substances in it, but there are some ionic ones too.
A compound. A compound can be covalent or ionic depending on which elements are bonding.
KCl is an ionic compound. The electronegativity of potassium (K) is approximately 0.82. The electronegativity of chlorine (Cl) is approximately 3.16. The difference between these electronegativities is 2.34. This high electronegativity difference is what makes potassium chloride an ionic compound. If the electronegativity difference of two elements is greater than 1.7, it is considered to be an ionic compound. If the difference is between 0.4 and 1.7, the compound is considered to be polar covalent. If the difference is less than 0.4, the compound is considered to be covalent. If the difference is 0 (i.e. the two elements are the same), then the compound is considered to be pure covalent. KCl is ionic because K's electronegativity is 0.82 and Cl's is 3.16. A compound is ionic when the electronegativity on the Pauling Scale is more than 2.1. The difference 2.34, so it is ionic.
Water molecule is polar covalent, but has a negligible ionic behavior.
Covalent bonds are the strongest in an aqueous solution.