What element has 3 valance electrons and 4 energy levels

What does measurement mean

A substance produced in a reaction

How many grams of nacl are in 500 ml of 1/2 ns? (answer must be numeric; no units or commas; include a leading zero when answer is less than 1.) ?

True for a group of cells is called an organ

What phase change is a type of. Physical change, chemical change, nuclear change, covalent change

Name 4 common chemical properties of matter

Why is photosynthesis so important to plants, and can't animals use it?

One way the government of Kim Jong-il controls the lives of the people who live in North Korea is by a. requiring every citizen to vote. b. controlling information its people receive from the outside world. c. enforcing free trade with other nations.

Give reasons 1) copper utensils and sheets become blackish after some days

Predict the spontaneity of a reaction (and the temperature dependence of the spontaneity) for each possible combination of signs for? H and? S (for the system).