Consider the following relational database that stores information about bars and customers: Drinker (name, address) Bar (name, address) Beer (name, brewer) Frequents (drinker, bar, times a week) Likes (drinker, beer) Serves (bar, beer, price) Write the following queries in relational algebra: 1. Find all drinkers who frequent only those bars that serve some beers they like. 2. Find all drinkers who frequent every bar that serves some beers they like.3. Find those drinkers who enjoy exactly the same set of beers as Amy.،​

answer: when the substance contain the two parts (polar and non-polar) like soap.

explanation:

soap is produced from the basic hydrolysis of ester "saponification", it is considered as a salt of hydrocarbons. the soap molecule contains the two parts: a polar group   (-coo-na+) and a non-polar group (r-hydrocarbon part). the polar group is called the head and the tail is the non-polar group. the polar group is hydrophilic in nature (water loving) and the non-polar group is hydrophobic in nature (water repelling).the polar/non-polar nature of a substance is useful that it can dissolve the non-polar substances by the polar part and also can dissolve the polar substances by the non-polar part. it commonly used in detergents and soaps.

Answer domain name system (dns);

Answer the car to the left must yield the right of way to the vehicle on the right;