What is the most difficult thing in chemistry to learn?

How do autotrophs (plants) recycle matter?

Iodine has a lower atomic weight than tellurium (126.90 for I, 127.60 for Te) even though it has a higher atomic number (53 for I, 52 for Te). Explain.

The isotope with 19 protons and 20 neutrons

A lead ball has a mass of 55.0 grams and a density of 11.4 g/cm3. What is the volume of the ball? A) 0.207 mL B) 0.207 L C) 4.82 mL D) 4.82 L E) none of the above

What Release cytokines to simulate other immune system components

A chemist has dissolved a certain substance in water. The chemist knows that more of the substance could be dissolved into the water before it stops dissolving. Therefore, the current solution is

Which of these particles is the smallest? A. an atom B. a nucleus C. a proton D. an electron

In a five-fold serial dilution of a 20 pg/ml solution, all tube dilutions are 1/5. What is the substance concentration in the third tube of this series?

Which of the following substances is never a Brønsted-Lowry base in an aqueous solution? Group of answer choicespotassium hydroxide, KOHsodium hydrogen phosphate, Na2HPO4sodium phosphate, Na3PO4ammonium chloride, NH4Clsodium bicarbonate, NaHCO3

Why is gold less reactive than iron?