Of the 20 amino acids, how many amino acids are considered essential? why are they called essential?

An empty erlenmeyer flask weighs 241.3 g. when filled with water (d=1.00 g/cm3), the flask and its contents weigh 489.1 g. what is the volume of water in the flask?

Which claim best supported by the data a b c or d

How is heat transfered between frozen fish sticks in the oven?

Give the mass percent of hydrogen in c14h19no2.

Which statement describes a chemical change? (1) Alcohol evaporates. (2) Water vapor forms snowflakes. (3) Table salt (NaCl) is crushed into powder. (4) Glucose (C6H12O6) and oxygen produce CO2 and H20.

Which of the following is the correct scientific notation for 0.000451 g? 4.5 x 10-3 4.5 x 10-5 4.51 x 10-4 45.1 x 10-4

A phase change from a solid to a gas is called what

What is hydrocarbon?

Why did most scientists reject Wegner's theory for nearly a half century?

Define prediction and explain how it is used to formulate a hypothesis.